For what typical tasks are hash functions used in Python and how are they used in standard libraries?

Hash functions in Python are used for quick comparison and data lookup, as well as for implementing data structures such as sets (set) and dictionaries (dict).

Main tasks:

• Fast equality check of objects via their hash.
• Using objects as keys in dictionaries and elements in sets.
• Implementing algorithms that require hashing (e.g., caching, deduplication).

In the standard library:

• The function hash(obj) returns an integer hash value of the object.
• Classes can override the __hash__() method to define their own hashing method.

Example of usage:

my_dict = {}
key = (1, 2, 3)  # Tuple — hashable object
my_dict[key] = "value"

print(hash(key))  # Prints the hash of the tuple

It is important that objects used as keys are immutable and have correctly implemented __hash__ and __eq__ methods.