Python/strings/lower.py

def lower(word: str) -> str:

    """
    Will convert the entire string to lowecase letters

    >>> lower("wow")
    'wow'
    >>> lower("HellZo")
    'hellzo'
    >>> lower("WHAT")
    'what'

    >>> lower("wh[]32")
    'wh[]32'
    >>> lower("whAT")
    'what'
    """

    # converting to ascii value int value and checking to see if char is a capital
    # letter if it is a capital letter it is getting shift by 32 which makes it a lower
    # case letter
    return "".join(
        chr(ord(char) + 32) if 65 <= ord(char) <= 90 else char for char in word
    )


if __name__ == "__main__":
    from doctest import testmod

    testmod()