from typing import List


def str_to_tokens(user_str: str) -> List[str]:
    """Split the given string into elements using the rules of separation.
    In our case the rule is simple, each token is separated by a comma (,)
    character.
    "Hello World, Yes, sir!" - will be transofrmed into:
    ["Hello World", "Yes", "sir!"]
    """
    return user_str.split(',')