def make_header(lines):
    """returns one header line from multiple header lines"""
    lengths = map(len, lines)
    max_length = max(lengths)
    for index, line in enumerate(lines):
        if lengths[index] != max_length:
            for i in range(lengths[index], max_length):
                line.append('')
    header = []
    for t, b in zip(*lines):
        if t.strip().endswith('-'):
            c = t.strip() + b
        else:
            c = ' '.join([t.strip(), b.strip()])
        header += [c.strip()]
    return header
