@classmethod
def config(cls, seps=None, allow_no_sep=None, figures=None, try_hard=None,
    use_formats=None, use_sformats=None):
    """
        Modify class-configuration.

        :keyword seps:              Allowed separators for formats.
        :keyword allow_no_sep:      Allows formats without any separator.
        :keyword try_hard:          Regardless of any configuration try hard to
                                    build formats for the given string.
        :keyword figures:           List of three booleans that predicts how many
                                    digits formats are allowed to have.

        :type seps:                 list
        :type allow_no_sep:         bool
        :type figures:              list
        """
    if seps:
        cls.SEPS = seps
    if not cls.isnone(allow_no_sep):
        cls.ALLOW_NO_SEP = allow_no_sep
    if not cls.isnone(use_formats):
        cls.USE_FORMATS = use_formats
    if not cls.isnone(use_sformats):
        cls.USE_SFORMATS = use_sformats
    if not cls.isnone(try_hard):
        cls.TRY_HARD = try_hard
    if figures:
        cls.FIGURES = figures
    if not any(cls.FIGURES):
        raise Exception('invalid configuration')
