Python, string,

def lower(word: str) -> str:
    Will convert the entire string to lowercase letters

    >>> lower("wow")
    >>> lower("HellZo")
    >>> lower("WHAT")
    >>> lower("wh[]32")
    >>> lower("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 "A" <= char <= "Z" else char for char in word)

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