def lowercase(text_string):
    '''
    Converts text_string into lowercase and returns the converted string as type str.

    Keyword argument:

    - text_string: string instance

    Exceptions raised:

    - InputError: occurs should a non-string argument be passed
    '''
    if text_string is None or text_string == "":
        return ""
    elif isinstance(text_string, str):
        return text_string.lower()
    else:
        raise InputError("string not passed as argument for text_string")
def lowercase ( text_string ) : if text_string is None or text_string == "" : return "" elif isinstance ( text_string , str ) : return text_string . lower ( ) else : raise InputError ( "string not passed as argument for text_string" )
Converts text_string into lowercase and returns the converted string as type str.

    Keyword argument:

    - text_string: string instance

    Exceptions raised:

    - InputError: occurs should a non-string argument be passed