create a String from this instance. Unless redefined, `a.as_string` will
create `"instance[T]"` where `T` is the dynamic type of `a`

Decode a percent encoded (url encoded) string into a sequence of bytes

The encoded input string may only contain the following characters
"A"-"Z", "a"-"z", "0"-"9", "-", ".", "_", "~", and "+"
or the string "%HH" where H is a hexadecimal digit (case insensitive).

Any other character or broken encoding will return an error.

* The alphanumeric characters "a" through "z", "A" through "Z" and "0" through "9",
as well as the special characters "-", ".", "_", and "~" are converted to the corresponding ascii value.
* Percent encoded bytes ("%HH") are simply converted to a byte.
* The plus character "+" is converted to the ascii value of the space character " ".

Decode a percent encoded (url encoded) utf8 string

The encoded input string may only contain the following characters
"A"-"Z", "a"-"z", "0"-"9", "-", ".", "_", "~", and "+"
or the string "%HH" where H is a hexadecimal digit (case insensitive).

Any other character or broken encoding will return an error.

* Percent encoded bytes ("%HH" where HH is the two-digit hexadecimal representation of the byte),
or sequences of those, are converted to the corresponding codepoint(s) in utf8
* The plus character "+" is converted to a space " ".

Decode a percent encoded (url encoded) utf8 string

Codepoint not allowed in percent encoded string are included in the output unmodified.
Broken percent encoded bytes still return an error.

* Percent encoded bytes ("%HH" where HH is the two-digit hexadecimal representation of the byte),
or sequences of those, are converted to the corresponding codepoint(s) in utf8
* The plus character "+" is converted to a space " ".

dynamic_apply -- apply `f.call` to `Any.this`'s dynamic type and value

This can be used to perform operation on values depending on their dynamic
type.

Here is an example that takes a `Sequence Any` that may contain boxed values
of types `i32` and `f64`. We can now write a feature `get_f64` that extracts
these values converted to `f64` and build a function `sum` that sums them up
as follows:


NYI: IMPROVEMENT: #5892: If this is fixed, we could write

Get the dynamic type of this instance. For value instances `x`, this is
equal to `type_of x`, but for `x` with a `ref` type `x.dynamic_type` gives
the actual runtime type, while `type_of x` results in the static
compile-time type.

There is no dynamic type of a type instance since this would result in an
endless hierarchy of types. So for Type values, dynamic_type is redefined
to just return Type.type.

Percent encode (url encode) a Sequence of bytes, as specified in RFC 3986 section 2.1

* Bytes values of a save (unreserved) character (A-Z, a-z, 0-9, "-", ".", "_" and "~") are encoded as that character.
* All other values are encoded as "%HH", where HH is the hexadecimal representation of the byte, using uppercase letters

Percent encode (url encode) an utf8 string, as specified in RFC 3986 section 2.1

* The alphanumeric characters "a" through "z", "A" through "Z" and "0" through "9" remain the same.
* The special characters "-", ".", "_", and "~" remain the same.
* All other characters are unsafe, their bytes are individually converted to a 3-character string "%HH",
where HH is the two-digit hexadecimal representation of the byte. This also applies to the space character.

convenience prefix operator to create a string from a value.

This permits usage of `$` as a prefix operator in a similar way both
inside and outside of constant strings: $x and "$x" will produce the
same string.

string representation of this type to be used for debugging.

result has the form "Type of '<name>'", but this might change in the future

There is no dynamic type of a type instance since this would result in an
endless hierarchy of types, so dynamic_type is redefined to just return
Type.type here.

Is this type assignable to a type parameter with constraint `T`?

The result of this is a compile-time constant that can be used to specialize
code for a particular type.


it is most useful in conjunction with preconditions or `if` statements as in


or

name of this type, including type parameters, e.g. 'option (list i32)'.

convenience prefix operator to create a string from a value.

This permits usage of `$` as a prefix operator in a similar way both
inside and outside of constant strings: $x and "$x" will produce the
same string.

NYI: Redefinition allows the type feature to be distinguished from its normal counterpart, see #3913

Get a type as a value.

This is a feature with the effect equivalent to Fuzion's `expr.type` call tail.
It is recommended to use `expr.type` and not `expr.type_value`.

`type_value` is here to show how this can be implemented and to illustrate the
difference to `dynamic_type`.