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Built-in types

These are examples of some of the most common built-in types:

Type Description
int integer
float floating point number
bool boolean value
str string (unicode)
bytes 8-bit string
object an arbitrary object (object is the common base class)
List[str] list of str objects
Tuple[int, int] tuple of two int objects (Tuple[()] is the empty tuple)
Tuple[int, ...] tuple of an arbitrary number of int objects
Dict[str, int] dictionary from str keys to int values
Iterable[int] iterable object containing ints
Sequence[bool] sequence of booleans (read-only)
Mapping[str, int] mapping from str keys to int values (read-only)
Any dynamically typed value with an arbitrary type

The type Any and type constructors such as List, Dict, Iterable and Sequence are defined in the typing module.

The type Dict is a generic class, signified by type arguments within [...]. For example, Dict[int, str] is a dictionary from integers to strings and Dict[Any, Any] is a dictionary of dynamically typed (arbitrary) values and keys. List is another generic class. Dict and List are aliases for the built-ins dict and list, respectively.

Iterable, Sequence, and Mapping are generic types that correspond to Python protocols. For example, a str object or a List[str] object is valid when Iterable[str] or Sequence[str] is expected. Note that even though they are similar to abstract base classes defined in collections.abc (formerly collections), they are not identical, since the built-in collection type objects do not support indexing.