def is_printable(ch):
    """
    Return True if character is displayable.
    """
    return (is_in_range(ch, str_to_ord('A'), str_to_ord('Z'))
            or is_in_range(ch, str_to_ord('a'), str_to_ord('z'))
            or is_in_range(ch, str_to_ord('0'), str_to_ord('9')))