def remove_tab(tab_length, lines):
    """
        Remove tab of `tab_length` from `lines`.
        Be sure to leave comments not removing their tab.
    """
    new_lines = []
    for line in lines:
        if line.strip().startswith('#'):
            new_lines.append(line)
        else:
            new_lines.append(line[tab_length:])
    return new_lines
