python type hints function code example

Example 1: python type hints

def no_type_hint(arg):
  print(arg) # arg can be anything
  
def with_type_hint(arg: str):
  print(arg) # arg must be a string or a subtype of string

Example 2: python typing list of strings

from typing import List

def my_func(l: List[int]):
    pass

Example 3: python optional type annotation

from custom_module import SomeClass
from typing import Optional

class SubClass:
    a_reference: Optional[SomeClass] # Provides info that a_reference may be 'None'.

    def __init__(self):
        self.a_reference = None