refs.items

Module nustd.kv.refs.items.

kv leaves: one value at one address, read and written whole.

ItemRef is the leaf itself (slot-level read, write, erase and observe over a kv leaf) and declares a slot once for every leaf. Each value leaf mixes one value form in beside it, so the ref is an operand of the value it names; the form decides the surface, the leaf decides where the value lives.

Name	Sort	Call	Meaning
BoolRef	`ref`	`BoolRef(address, parent_ref=None, owner_shape=None)`	A bool leaf in KV storage, carrying the whole Bool logical surface.
BytesRef	`ref`	`BytesRef(address, parent_ref=None, owner_shape=None)`	A bytes leaf in KV storage, carrying the whole Bytes operator surface.
FloatRef	`ref`	`FloatRef(address, parent_ref=None, owner_shape=None)`	A float leaf in KV storage, carrying the whole Float operator surface.
IntRef	`ref`	`IntRef(address, parent_ref=None, owner_shape=None)`	An int leaf in KV storage, carrying the whole Int operator surface.
ObjectRef	`ref`	`ObjectRef(address, parent_ref=None, owner_shape=None)`	A leaf in KV storage holding a value of no declared type.
StrRef	`ref`	`StrRef(address, parent_ref=None, owner_shape=None)`	A str leaf in KV storage, carrying the whole Str operator surface.

BoolRef

A bool leaf in KV storage, carrying the whole Bool logical surface.

BoolRef(address, parent_ref=None, owner_shape=None)

Path nustd.kv.BoolRef. Kind Ref, sort ref, cardinality scalar.

Notes

Stored as a plain bool, so nothing is translated on read or write.
An absent leaf reads as EMPTY, which is not False; test with exists or is_empty when the difference matters.

Example

class Flags(Shape):
    live = BoolRef.slot()
run(Flags.live.set(True), ctx)
run(Flags.live.not_(), ctx)

Inherited methods

From nu.domains.shape.item.ReactiveItemForm:

Call	Builds	Meaning
`.on_change()`	`OnPrimitiveChange`	Subscribe to changes on this leaf.

From nu.domains.shape.item.MutableItemForm:

Call	Builds	Meaning
`.set(value)`	`SetCmd`	Build a `SetCmd`.
`.erase()`	`Erase`	Build an `Erase`.
`.init(value)`	`IfDo`	Set `value` iff the leaf is currently missing.

From nu.domains.shape.item.ItemForm:

Call	Builds	Meaning
`.exists()`	`Bool`	Whether this slot holds a value, as a `Bool`.
`.missing()`	`Bool`	Whether this slot holds no value, as a `Bool`: the negation of `exists()`.

From nu.forms.primitives.bool_.Bool:

Call	Builds	Meaning
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.fallback(*alternatives)`	`Self`	The first of this value and `alternatives` that is not EMPTY.

BytesRef

A bytes leaf in KV storage, carrying the whole Bytes operator surface.

BytesRef(address, parent_ref=None, owner_shape=None)

Path nustd.kv.BytesRef. Kind Ref, sort ref, cardinality scalar.

Notes

Stored as plain bytes, so nothing is translated on read or write.
The leaf a raw payload belongs in: no decoding happens on the way through, unlike the std refs that serialize a domain type.

Example

class Blob(Shape):
    raw = BytesRef.slot()
run(Blob.raw.set(b"payload"), ctx)
run(Blob.raw.hex_(), ctx)

Inherited methods

From nu.domains.shape.item.ReactiveItemForm:

Call	Builds	Meaning
`.on_change()`	`OnPrimitiveChange`	Subscribe to changes on this leaf.

From nu.domains.shape.item.MutableItemForm:

Call	Builds	Meaning
`.set(value)`	`SetCmd`	Build a `SetCmd`.
`.erase()`	`Erase`	Build an `Erase`.
`.init(value)`	`IfDo`	Set `value` iff the leaf is currently missing.

From nu.domains.shape.item.ItemForm:

Call	Builds	Meaning
`.exists()`	`Bool`	Whether this slot holds a value, as a `Bool`.
`.missing()`	`Bool`	Whether this slot holds no value, as a `Bool`: the negation of `exists()`.

From nu.forms.primitives.bytes_.Bytes:

Call	Builds	Meaning
`a + b`	`Bytes`	Concatenation of self and other.
`a[key]`	`Bytes \| Int`	Byte at an index, or a sub-range by slice.
`.len()`	`Int`	Length of self in bytes.
`.contains(item)`	`Bool`	Substring test: item in self.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.
`.decode(encoding='utf-8')`	`Str`	Decode self to a string using the given encoding.
`.hex_()`	`Str`	Hex string of self, two digits per byte.
`.upper()`	`Bytes`	Self with ASCII letters uppercased.
`.lower()`	`Bytes`	Self with ASCII letters lowercased.
`.strip(chars=None)`	`Bytes`	Self with leading and trailing bytes removed.
`.lstrip(chars=None)`	`Bytes`	Self with leading bytes removed.
`.rstrip(chars=None)`	`Bytes`	Self with trailing bytes removed.
`.split_bytes(sep=None, maxsplit=-1)`	`List`	Self split into a List of Bytes on sep.
`.find_bytes(sub, start=0, end=None)`	`Int`	Lowest index of sub in self, or -1 if absent.
`.count_bytes(sub)`	`Int`	Number of non-overlapping occurrences of sub in self.
`.startswith(prefix)`	`Bool`	Self starts with prefix.
`.endswith(suffix)`	`Bool`	Self ends with suffix.
`.replace(old, new, count=-1)`	`Bytes`	Self with occurrences of old replaced by new.
`.removeprefix(prefix)`	`Bytes`	Self with prefix removed if present.
`.removesuffix(suffix)`	`Bytes`	Self with suffix removed if present.
`.translate(table, delete=b'')`	`Bytes`	Self translated through a 256-byte table, with bytes in delete dropped first.
`.title()`	`Bytes`	Self titlecased: each word's first cased byte upper, the rest lower.
`.capitalize()`	`Bytes`	Self with the first byte uppercased and the rest lowercased.
`.swapcase()`	`Bytes`	Self with uppercase and lowercase bytes swapped.
`.rsplit_bytes(sep=None, maxsplit=-1)`	`List`	Self split into a List of Bytes on sep, counting maxsplit from the right.
`.splitlines(keepends=False)`	`List`	Self split into a List of Bytes at line boundaries.
`.partition(sep)`	`Tuple`	Self split around the first occurrence of sep.
`.rpartition(sep)`	`Tuple`	Self split around the last occurrence of sep.
`.rfind_bytes(sub, start=0, end=None)`	`Int`	Highest index of sub in self, or -1 if absent.
`.index_bytes(sub, start=0, end=None)`	`Int`	Lowest index of sub in self.
`.rindex_bytes(sub, start=0, end=None)`	`Int`	Highest index of sub in self.
`.isascii()`	`Bool`	Self has only ASCII bytes.
`.isdigit()`	`Bool`	Self has only ASCII digit bytes, and at least one.
`.isalpha()`	`Bool`	Self has only ASCII letter bytes, and at least one.
`.isalnum()`	`Bool`	Self has only ASCII alphanumeric bytes, and at least one.
`.isspace()`	`Bool`	Self has only ASCII whitespace bytes, and at least one.
`.istitle()`	`Bool`	Self is titlecased, with at least one cased byte.
`.isupper()`	`Bool`	Self has all cased bytes uppercase, and at least one cased byte.
`.islower()`	`Bool`	Self has all cased bytes lowercase, and at least one cased byte.
`.center(width, fillbyte=b' ')`	`Bytes`	Self centered in a field of width, padded with fillbyte.
`.ljust(width, fillbyte=b' ')`	`Bytes`	Self left-justified in a field of width, padded with fillbyte.
`.rjust(width, fillbyte=b' ')`	`Bytes`	Self right-justified in a field of width, padded with fillbyte.
`.zfill(width)`	`Bytes`	Self padded with leading zero bytes to width.
`.expandtabs(tabsize=8)`	`Bytes`	Self with tab bytes expanded to spaces.
`.join(iterable)`	`Bytes`	Self used as separator between the elements of iterable.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.fallback(*alternatives)`	`Self`	The first of this value and `alternatives` that is not EMPTY.

FloatRef

A float leaf in KV storage, carrying the whole Float operator surface.

FloatRef(address, parent_ref=None, owner_shape=None)

Path nustd.kv.FloatRef. Kind Ref, sort ref, cardinality scalar.

Notes

Stored as a plain float, so nothing is translated on read or write.
Reach for DecimalRef instead when the value is money or anything else that must round-trip exactly.

Example

class Order(Shape):
    price = FloatRef.slot()
run(Order.price.set(12.5), ctx)

Inherited methods

From nu.domains.shape.item.ReactiveItemForm:

Call	Builds	Meaning
`.on_change()`	`OnPrimitiveChange`	Subscribe to changes on this leaf.

From nu.domains.shape.item.MutableItemForm:

Call	Builds	Meaning
`.set(value)`	`SetCmd`	Build a `SetCmd`.
`.erase()`	`Erase`	Build an `Erase`.
`.init(value)`	`IfDo`	Set `value` iff the leaf is currently missing.

From nu.domains.shape.item.ItemForm:

Call	Builds	Meaning
`.exists()`	`Bool`	Whether this slot holds a value, as a `Bool`.
`.missing()`	`Bool`	Whether this slot holds no value, as a `Bool`: the negation of `exists()`.

From nu.forms.primitives.float_.Float:

Call	Builds	Meaning
`a + b`	`Float`	Sum of self and other.
`a - b`	`Float`	Self minus other.
`a * b`	`Float`	Product of self and other.
`a / b`	`Float`	Self divided by other.
`a // b`	`Float`	Self floor-divided by other.
`a % b`	`Float`	Self modulo other.
`a ** b`	`Float`	Self raised to the other power.
`-a`	`Float`	Negation of self.
`+a`	`Float`	Self unchanged.
`abs(a)`	`Float`	Absolute value of self.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.fallback(*alternatives)`	`Self`	The first of this value and `alternatives` that is not EMPTY.

IntRef

An int leaf in KV storage, carrying the whole Int operator surface.

IntRef(address, parent_ref=None, owner_shape=None)

Path nustd.kv.IntRef. Kind Ref, sort ref, cardinality scalar.

Notes

Stored as a plain int, so the stored form and the value form are the same and nothing is translated on the way in or out.
Arithmetic on the ref builds an expression over the stored value; writing the result back is what set, inc and dec do.

Example

class Counter(Shape):
    hits = IntRef.slot()
run(Counter.hits.set(0), ctx)
run(Counter.hits.inc(), ctx)

Methods

`.inc(step=1)`

Add step to the stored int and write the result back.

Builds None_.

Arguments

Name	Type	Default	Meaning
`step`	`IntArg`	`1`	how much to add. May be an expression, not just a literal.

Notes

Read-modify-write in one term, not a storage-level atomic increment; wrap it in a transaction when concurrent writers can touch the same leaf.
An absent leaf reads as EMPTY, so the addition is EMPTY and the write refuses to store it. Set the slot before incrementing it.

Example

run(Counter.hits.inc(), ctx)

`.dec(step=1)`

Subtract step from the stored int and write the result back.

Builds None_.

Arguments

Name	Type	Default	Meaning
`step`	`IntArg`	`1`	how much to subtract. May be an expression.

Notes

Same read-modify-write shape as inc, and the same refusal to store a sentinel when the leaf is absent.

Example

run(Counter.hits.dec(2), ctx)

Inherited methods

From nu.domains.shape.item.ReactiveItemForm:

Call	Builds	Meaning
`.on_change()`	`OnPrimitiveChange`	Subscribe to changes on this leaf.

From nu.domains.shape.item.MutableItemForm:

Call	Builds	Meaning
`.set(value)`	`SetCmd`	Build a `SetCmd`.
`.erase()`	`Erase`	Build an `Erase`.
`.init(value)`	`IfDo`	Set `value` iff the leaf is currently missing.

From nu.domains.shape.item.ItemForm:

Call	Builds	Meaning
`.exists()`	`Bool`	Whether this slot holds a value, as a `Bool`.
`.missing()`	`Bool`	Whether this slot holds no value, as a `Bool`: the negation of `exists()`.

From nu.forms.primitives.int_.Int:

Call	Builds	Meaning
`a + b`	`Int \| Float`	Sum of self and other.
`a - b`	`Int \| Float`	Self minus other.
`a * b`	`Int \| Float`	Product of self and other.
`a / b`	`Float`	Self divided by other.
`a // b`	`Int \| Float`	Self floor-divided by other.
`a % b`	`Int \| Float`	Self modulo other.
`a ** b`	`Int \| Float`	Self raised to the other power.
`-a`	`Int`	Negation of self.
`+a`	`Int`	Self unchanged.
`abs(a)`	`Int`	Absolute value of self.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.
`.bitand(other)`	`Int`	Bitwise AND of self and other.
`.bitor(other)`	`Int`	Bitwise OR of self and other.
`.bitxor(other)`	`Int`	Bitwise XOR of self and other.
`.bitnot()`	`Int`	Bitwise NOT of self.
`.lshift(other)`	`Int`	Self shifted left by other bits.
`.rshift(other)`	`Int`	Self shifted right by other bits.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.fallback(*alternatives)`	`Self`	The first of this value and `alternatives` that is not EMPTY.

ObjectRef

A leaf in KV storage holding a value of no declared type.

ObjectRef(address, parent_ref=None, owner_shape=None)

Path nustd.kv.ObjectRef. Kind Ref, sort ref, cardinality scalar.

What a container descends to when its value is object, undeclared, or a type with no kv leaf of its own. It carries the whole Object surface, so the ref is still an operand: == builds an Eq, attribute and subscript access descend into the value read, and a cast narrows it.

Notes

A dict or list stored here reads back as a plain value, not a View.

Example

class Bag(Shape):
    meta = DictRef.slot(object)
run(Bag.meta["title"] == "hello", ctx)
run(nu.Str(Bag.meta["title"]).upper(), ctx)

Inherited methods

From nu.domains.shape.item.ReactiveItemForm:

Call	Builds	Meaning
`.on_change()`	`OnPrimitiveChange`	Subscribe to changes on this leaf.

From nu.domains.shape.item.MutableItemForm:

Call	Builds	Meaning
`.set(value)`	`SetCmd`	Build a `SetCmd`.
`.erase()`	`Erase`	Build an `Erase`.
`.init(value)`	`IfDo`	Set `value` iff the leaf is currently missing.

From nu.domains.shape.item.ItemForm:

Call	Builds	Meaning
`.exists()`	`Bool`	Whether this slot holds a value, as a `Bool`.
`.missing()`	`Bool`	Whether this slot holds no value, as a `Bool`: the negation of `exists()`.

From nu.forms.primitives.object_.Object:

Call	Builds	Meaning
`a + b`	`Object`	Sum of self and other.
`a - b`	`Object`	Self minus other.
`a * b`	`Object`	Product of self and other.
`a @ b`	`Object`	Matrix multiplication: self @ other.
`a / b`	`Object`	Self divided by other.
`a // b`	`Object`	Self floor-divided by other.
`a % b`	`Object`	Self modulo other.
`a ** b`	`Object`	Self raised to the other power.
`-a`	`Object`	Negation of self.
`+a`	`Object`	Self unchanged.
`abs(a)`	`Object`	Absolute value of self.
`a > b`	`Bool`	Self strictly greater than other.
`a < b`	`Bool`	Self strictly less than other.
`a >= b`	`Bool`	Self greater than or equal to other.
`a <= b`	`Bool`	Self less than or equal to other.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.
`.bitand(other)`	`Object`	Python's `&` on the values: bits for ints, intersection for sets.
`.bitor(other)`	`Object`	Python's `\|` on the values: bits for ints, union for sets, merge for dicts.
`.bitxor(other)`	`Object`	Python's `^` on the values: bits for ints, symmetric difference for sets.
`.bitnot()`	`Object`	Python's `~` on the value.
`.lshift(other)`	`Object`	Self shifted left by other bits: Python's `<<` on the values.
`.rshift(other)`	`Object`	Self shifted right by other bits: Python's `>>` on the values.
`.union(other)`	`Object`	Set union of self and other.
`.intersection(other)`	`Object`	Set intersection of self and other.
`.difference(other)`	`Object`	Elements of self that are not in other.
`.symmetric_difference(other)`	`Object`	Elements in exactly one of self and other.
`.merge(other)`	`Object`	Self and other merged into a new mapping: Python's dict `\|`.
`a[key]`	`Object`	Subscript access: self[key].
`.len()`	`Int`	Length of self.
`.contains(item)`	`Bool`	Membership test: item in self.
`.iter()`	`Iterator`	Lazy iterator stream over self's elements.
`.has_attr(name)`	`Bool`	Attribute presence: hasattr(self, name).

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.fallback(*alternatives)`	`Self`	The first of this value and `alternatives` that is not EMPTY.

StrRef

A str leaf in KV storage, carrying the whole Str operator surface.

StrRef(address, parent_ref=None, owner_shape=None)

Path nustd.kv.StrRef. Kind Ref, sort ref, cardinality scalar.

Notes

Stored as a plain str, so nothing is translated on read or write.
Doubles as a key source: a str leaf can be the address of another ref, and it is resolved when the path is walked.

Example

class Portfolio(Shape):
    name = StrRef.slot()
run(Portfolio.name.set("core"), ctx)
run(Portfolio.name.upper(), ctx)

Inherited methods

From nu.domains.shape.item.ReactiveItemForm:

Call	Builds	Meaning
`.on_change()`	`OnPrimitiveChange`	Subscribe to changes on this leaf.

From nu.domains.shape.item.MutableItemForm:

Call	Builds	Meaning
`.set(value)`	`SetCmd`	Build a `SetCmd`.
`.erase()`	`Erase`	Build an `Erase`.
`.init(value)`	`IfDo`	Set `value` iff the leaf is currently missing.

From nu.domains.shape.item.ItemForm:

Call	Builds	Meaning
`.exists()`	`Bool`	Whether this slot holds a value, as a `Bool`.
`.missing()`	`Bool`	Whether this slot holds no value, as a `Bool`: the negation of `exists()`.

From nu.forms.primitives.str_.Str:

Call	Builds	Meaning
`a + b`	`Str`	Concatenation of self and other.
`a[key]`	`Str`	Character at an int index, or substring for a slice.
`.len()`	`Int`	Length of self in characters.
`.contains(item)`	`Bool`	Substring test: item in self.
`a > b`	`Bool`	Self strictly greater than other, lexicographically.
`a < b`	`Bool`	Self strictly less than other, lexicographically.
`a >= b`	`Bool`	Self greater than or equal to other, lexicographically.
`a <= b`	`Bool`	Self less than or equal to other, lexicographically.
`a == b`	`Bool`	Self equal to other by value.
`a != b`	`Bool`	Self not equal to other by value.
`.is_(other)`	`Bool`	Identity comparison: self is other.
`.and_(other)`	`Bool`	Logical AND of self and other.
`.or_(other)`	`Bool`	Logical OR of self and other.
`.not_()`	`Bool`	Logical NOT of self.
`.bool_()`	`Bool`	Cast self to Bool.
`.upper()`	`Str`	Self converted to uppercase.
`.lower()`	`Str`	Self converted to lowercase.
`.title()`	`Str`	Self converted to title case.
`.capitalize()`	`Str`	Self with only the first character capitalized.
`.swapcase()`	`Str`	Self with uppercase and lowercase characters swapped.
`.casefold()`	`Str`	Self folded for aggressive, caseless matching.
`.strip(chars=None)`	`Str`	Self with leading and trailing characters removed.
`.lstrip(chars=None)`	`Str`	Self with leading characters removed.
`.rstrip(chars=None)`	`Str`	Self with trailing characters removed.
`.split(sep=None, maxsplit=-1)`	`List`	Self split into a list on sep, from the left.
`.rsplit(sep=None, maxsplit=-1)`	`List`	Self split into a list on sep, from the right.
`.splitlines(keepends=False)`	`List`	Self split into a list at line boundaries.
`.partition(sep)`	`Tuple`	Self split around the first occurrence of sep into a 3-tuple.
`.rpartition(sep)`	`Tuple`	Self split around the last occurrence of sep into a 3-tuple.
`.find(sub, start=0, end=None)`	`Int`	Lowest index in self where sub is found, searching from the left.
`.rfind(sub, start=0, end=None)`	`Int`	Highest index in self where sub is found, searching from the right.
`.index(sub, start=0, end=None)`	`Int`	Lowest index in self where sub is found, searching from the left.
`.rindex(sub, start=0, end=None)`	`Int`	Highest index in self where sub is found, searching from the right.
`.count_substring(sub)`	`Int`	Count of non-overlapping occurrences of sub in self.
`.startswith(prefix)`	`Bool`	Whether self starts with prefix.
`.endswith(suffix)`	`Bool`	Whether self ends with suffix.
`.isdigit()`	`Bool`	Whether every character in self is a digit.
`.isalpha()`	`Bool`	Whether every character in self is alphabetic.
`.isalnum()`	`Bool`	Whether every character in self is alphanumeric.
`.isspace()`	`Bool`	Whether every character in self is whitespace.
`.isnumeric()`	`Bool`	Whether every character in self is numeric.
`.isdecimal()`	`Bool`	Whether every character in self is a decimal character.
`.isidentifier()`	`Bool`	Whether self is a valid Python identifier.
`.isprintable()`	`Bool`	Whether every character in self is printable.
`.istitle()`	`Bool`	Whether self is titlecased.
`.isupper()`	`Bool`	Whether every cased character in self is uppercase.
`.islower()`	`Bool`	Whether every cased character in self is lowercase.
`.isascii()`	`Bool`	Whether every character in self is ASCII.
`.center(width, fillchar=' ')`	`Str`	Self centered in a field of the given width.
`.ljust(width, fillchar=' ')`	`Str`	Self left-justified in a field of the given width.
`.rjust(width, fillchar=' ')`	`Str`	Self right-justified in a field of the given width.
`.zfill(width)`	`Str`	Self padded with leading zeros to the given width.
`.expandtabs(tabsize=8)`	`Str`	Self with tab characters expanded to spaces.
`.replace(old, new, count=-1)`	`Str`	Self with occurrences of old replaced by new.
`.removeprefix(prefix)`	`Str`	Self with the given prefix removed if present.
`.removesuffix(suffix)`	`Str`	Self with the given suffix removed if present.
`.translate(table)`	`Str`	Self with characters mapped through a translation table.
`.format_map(mapping)`	`Str`	Self formatted with `{field}` placeholders filled from mapping.
`.encode(encoding='utf-8')`	`Bytes`	Self encoded to Bytes.
`.join(iterable)`	`Str`	Elements of iterable joined together with self as separator.

From nu.lang.forms.Form:

Call	Builds	Meaning
`.is_empty()`	`Bool`	True if this Form yields the EMPTY sentinel.
`.not_empty()`	`Bool`	True if this Form does not yield EMPTY.
`.fallback(*alternatives)`	`Self`	The first of this value and `alternatives` that is not EMPTY.

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