Question

How do you use the hash method?

>>> def foo():
>>>    return 'foo'
>>> f = foo()
>>>
>>> hash(f)
-4177197833195190597
>>>
>>> hash(foo)
1643374
>>>
>>> hash(foo())
-4177197833195190597

For what do I could use it?

Answer 1

From the docs:

Return the hash value of the object (if it has one).
Hash values are integers. They are used to quickly compare dictionary
keys during a dictionary lookup. Numeric values that compare equal
have the same hash value (even if they are of different types, as is
the case for 1 and 1.0).