code: def generate_signature_class(cls):
      
      return type("%sSigs" % cls.__name__, (Base,),
                  {'__tablename__': "%s_sigs" % cls.__tablename__,
                   'id': sa.Column(sa.Integer,
                                   sa.Sequence('%s_id_seq' % cls.__tablename__),
                                   primary_key=True,
                                   doc="primary key"),
                   'data': sa.Column(sa.Text(), nullable=False,
                                     doc="The signed data"),
                   '%s_id' % cls.__tablename__: sa.Column(sa.Integer,
                                                          sa.ForeignKey("%s.id" % cls.__tablename__),
                                                          nullable=False)})
docs: Generate a declarative model for storing signatures related to the given
      cls parameter.
  
      :param class cls: The declarative model to generate a signature class for.
      :return: The signature class, as a declarative derived from Base.