def str_banner(txt=None, c='-', prefix='#', debug=True, label=None, color=None
    ):
    """
    prints a banner of the form with a frame of # around the txt::

    # --------------------------
    # txt
    # --------------------------

    :param color: prints in the given color
    :param label: adds a label
    :param debug: prints only if debug is true
    :param txt: a text message to be printed
    :type txt: string
    :param c: the character used instead of c
    :type c: character
    """
    output = ''
    if debug:
        output = '\n'
        output += prefix + ' ' + 70 * c + '\n'
        if label is not None:
            output += prefix + ' ' + label + '\n'
            output += prefix + ' ' + 70 * c + '\n'
        if txt is not None:
            for line in txt.splitlines():
                output += prefix + ' ' + line + '\n'
            output += prefix + ' ' + 70 * c + '\n'
    if color is None:
        color = 'BLUE'
    return output
