How to use the tespy.tools.data_containers.dc_cp function in tespy

for cp in self.comps.index:
            if cp.local_design is False:
                # unset variables provided in .design attribute
                for var in cp.design:
                    cp.get_attr(var).set_attr(is_set=False)

                switched = False
                msg = 'Set component attributes '

                for var in cp.offdesign:
                    # set variables provided in .offdesign attribute
                    data = cp.get_attr(var)
                    data.set_attr(is_set=True)

                    # take nominal values from design point
                    if isinstance(data, dc.dc_cp):
                        cp.get_attr(var).val = cp.get_attr(var).design
                        switched = True
                        msg += var + ', '

                if switched:
                    msg = (msg[:-2] + ' to design value at component ' +
                           cp.label + '.')
                    logging.debug(msg)

            # start component initialisation
            cp.comp_init(self)
            cp.new_design = False

        msg = 'Switched components from design to offdesign.'
        logging.debug(msg)

def attr():
        return {'P': dc_cp(min_val=0),
                'Q': dc_cp(max_val=0),
                'eta': dc_cp(min_val=0, max_val=1),
                'e': dc_cp(),
                'pr_c': dc_cp(max_val=1),
                'zeta': dc_cp(min_val=0),
                'eta_char': dc_cc(),
                'S': dc_simple()}

def attr():
        return {'P': dc_cp(min_val=0),
                'Q': dc_cp(max_val=0),
                'eta': dc_cp(min_val=0, max_val=1),
                'e': dc_cp(),
                'pr_c': dc_cp(max_val=1),
                'zeta': dc_cp(min_val=0),
                'eta_char': dc_cc(),
                'S': dc_simple()}

# unset design parameters
                for var in cp.design:
                    cp.get_attr(var).set_attr(is_set=False)

                # set offdesign parameters
                switched = False
                msg = 'Set component attributes '

                for var in cp.offdesign:
                    # set variables provided in .offdesign attribute
                    data = cp.get_attr(var)
                    data.set_attr(is_set=True)

                    # take nominal values from design point
                    if isinstance(data, dc.dc_cp):
                        cp.get_attr(var).val = cp.get_attr(var).design
                        switched = True
                        msg += var + ', '

                if switched:
                    msg = (msg[:-2] + ' to design value at component ' +
                           cp.label + '.')
                    logging.debug(msg)

                cp.new_design = False

            else:
                # switch connections to design mode
                if self.redesign is True:
                    for var in cp.design:
                        cp.get_attr(var).set_attr(is_set=True)

def attr():
        return {
            'Q': dc_cp(max_val=0), 'kA': dc_cp(min_val=0),
            'td_log': dc_cp(min_val=0),
            'ttd_u': dc_cp(min_val=0), 'ttd_l': dc_cp(min_val=0),
            'pr1': dc_cp(max_val=1), 'pr2': dc_cp(max_val=1),
            'zeta1': dc_cp(min_val=0), 'zeta2': dc_cp(min_val=0),
            'subcooling': dc_simple(val=False),
            'kA_char': dc_simple(),
            'kA_char1': dc_cc(param='m'), 'kA_char2': dc_cc(param='m'),
            'SQ1': dc_simple(), 'SQ2': dc_simple(), 'Sirr': dc_simple(),
        }

def attr():
        return {'P': dc_cp(), 'pr': dc_cp(), 'Sirr': dc_simple()}

def attr():
        return {
            'P': dc_cp(min_val=0),
            'eta_s': dc_cp(min_val=0, max_val=1),
            'eta_s_char': dc_cc(param='m'),
            'pr': dc_cp(min_val=1),
            'igva': dc_cp(min_val=-90, max_val=90, d=1e-3, val=0),
            'char_map': dc_cm(),
            'Sirr': dc_simple()
        }

def attr():
        return {
            'Q': dc_cp(max_val=0), 'kA': dc_cp(min_val=0),
            'td_log': dc_cp(min_val=0),
            'ttd_u': dc_cp(min_val=0), 'ttd_l': dc_cp(min_val=0),
            'pr1': dc_cp(max_val=1), 'pr2': dc_cp(max_val=1),
            'zeta1': dc_cp(min_val=0), 'zeta2': dc_cp(min_val=0),
            'subcooling': dc_simple(val=False),
            'kA_char': dc_simple(),
            'kA_char1': dc_cc(param='m'), 'kA_char2': dc_cc(param='m'),
            'SQ1': dc_simple(), 'SQ2': dc_simple(), 'Sirr': dc_simple(),
        }

def attr():
        return {
            'P': dc_cp(max_val=0),
            'eta_s': dc_cp(min_val=0, max_val=1),
            'eta_s_char': dc_cc(param='m'),
            'pr': dc_cp(min_val=0, max_val=1),
            'cone': dc_simple(),
            'Sirr': dc_simple()
        }

def attr():
        return {
            'Q': dc_cp(),
            'pr': dc_cp(min_val=1e-4, max_val=1), 'zeta': dc_cp(min_val=0),
            'D': dc_cp(min_val=1e-2, max_val=2, d=1e-4),
            'L': dc_cp(min_val=1e-1, d=1e-3),
            'ks': dc_cp(val=1e-4, min_val=1e-7, max_val=1e-4, d=1e-8),
            'E': dc_cp(min_val=0), 'A': dc_cp(min_val=0),
            'eta_opt': dc_cp(min_val=0, max_val=1),
            'lkf_lin': dc_cp(min_val=0), 'lkf_quad': dc_cp(min_val=0),
            'Tamb': dc_simple(),
            'Q_loss': dc_cp(min_val=0), 'SQ': dc_simple(),
            'hydro_group': dc_gcp(), 'energy_group': dc_gcp()
        }