def _ljust(input, width, fillchar=None):
    """Either ljust on a string or a list of string. Extend with fillchar."""
    if fillchar is None:
        fillchar = ' '
    if isinstance(input, str):
        return input.ljust(width, fillchar)
    else:
        delta_len = width - len(input)
        if delta_len <= 0:
            return input
        else:
            return input + [fillchar for _ in range(delta_len)]