def clean_lines(lines, lstrip=None, rstrip=None, remove_empty=True,
    remove_comments=True):
    """
    clean lines (usually read from a config file):

    1. strip whitespace (left and right), 2. remove empty lines, 3. remove comments.

    note: only "pure comment lines" are supported, no support for "trailing comments".

    :param lines: input line iterator (e.g. list or open text file) that gives unclean input lines
    :param lstrip: lstrip call arguments or False, if lstripping is not desired
    :param rstrip: rstrip call arguments or False, if rstripping is not desired
    :param remove_comments: remove comment lines (lines starting with "#")
    :param remove_empty: remove empty lines
    :return: yields processed lines
    """
    for line in lines:
        if lstrip is not False:
            line = line.lstrip(lstrip)
        if rstrip is not False:
            line = line.rstrip(rstrip)
        if remove_empty and not line:
            continue
        if remove_comments and line.startswith('#'):
            continue
        yield line
