How Do Python Functions Handle Returns: `None`, Implicit `None`, and No Return at All?

Python Return, None Return, and No Return

In Python, functions can return values to allow for later use or to indicate the success or failure of an operation. There are three ways to accomplish this: returning None, returning without a specified value, and not using a return statement at all.

Return None

The return None statement explicitly returns the value None. This is typically used when a function is intended to return a value, but there is no meaningful value to provide. For example:

def get_mother(person):
    if is_human(person):
        return person.mother
    else:
        return None

Return

The return statement without a specified value exits the function and returns None. This is typically used when the function's purpose is to modify state or raise an exception. For example:

def find_prisoner_with_knife(prisoners):
    for prisoner in prisoners:
        if "knife" in prisoner.items:
            prisoner.move_to_inquisition()
            return  # Exit the function, indicating the knife was found

    raise_alert()  # Raise an alert if no knife is found

No Return

When no return statement is used, the function implicitly returns None without the need for an explicit return None statement. This is typically used when the function's purpose is to simply execute a set of actions and does not need to return any value. For example:

def set_mother(person, mother):
    if is_human(person):
        person.mother = mother

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