How to use the thermo.activity.Pdew_mixture function in thermo

self.wsl = zs_to_ws(self.xs, self.MWs)
                self.wsg = zs_to_ws(self.ys, self.MWs)
                
                ng = self.V_over_F
                nl = (1. - self.V_over_F)
                self.MWl = mixing_simple(self.xs, self.MWs)
                self.MWg = mixing_simple(self.ys, self.MWs)
                self.x = self.quality = ng*self.MWg/(nl*self.MWl + ng*self.MWg)

            self.Pbubble_methods = Pbubble_mixture(T=self.T, zs=self.zs, Psats=self.Psats, CASRNs=self.CASs, AvailableMethods=True)
            self.Pbubble_method = self.Pbubble_methods[0]
            self.Pbubble = Pbubble_mixture(T=self.T, zs=self.zs, Psats=self.Psats, CASRNs=self.CASs, Method=self.Pbubble_method)

            self.Pdew_methods = Pdew_mixture(T=self.T, zs=self.zs, Psats=self.Psats, CASRNs=self.CASs, AvailableMethods=True)
            self.Pdew_method = self.Pdew_methods[0]
            self.Pdew = Pdew_mixture(T=self.T, zs=self.zs, Psats=self.Psats, CASRNs=self.CASs, Method=self.Pdew_method)
            if not None in self.Hs:
                self.H = mixing_simple(self.Hs, self.ws)
                self.Hm = property_mass_to_molar(self.H, self.MW)

            if not None in self.Ss:
                # Ideal gas contribution
                self.Sm = mixing_simple(self.Sms, self.zs) - R*sum([zi*log(zi) for zi in self.zs if zi > 0])
                self.S = property_molar_to_mass(self.Sm, self.MW)
        except:
            pass

if self.phase == 'two-phase':
                self.wsl = zs_to_ws(self.xs, self.MWs)
                self.wsg = zs_to_ws(self.ys, self.MWs)
                
                ng = self.V_over_F
                nl = (1. - self.V_over_F)
                self.MWl = mixing_simple(self.xs, self.MWs)
                self.MWg = mixing_simple(self.ys, self.MWs)
                self.x = self.quality = ng*self.MWg/(nl*self.MWl + ng*self.MWg)

            self.Pbubble_methods = Pbubble_mixture(T=self.T, zs=self.zs, Psats=self.Psats, CASRNs=self.CASs, AvailableMethods=True)
            self.Pbubble_method = self.Pbubble_methods[0]
            self.Pbubble = Pbubble_mixture(T=self.T, zs=self.zs, Psats=self.Psats, CASRNs=self.CASs, Method=self.Pbubble_method)

            self.Pdew_methods = Pdew_mixture(T=self.T, zs=self.zs, Psats=self.Psats, CASRNs=self.CASs, AvailableMethods=True)
            self.Pdew_method = self.Pdew_methods[0]
            self.Pdew = Pdew_mixture(T=self.T, zs=self.zs, Psats=self.Psats, CASRNs=self.CASs, Method=self.Pdew_method)
            if not None in self.Hs:
                self.H = mixing_simple(self.Hs, self.ws)
                self.Hm = property_mass_to_molar(self.H, self.MW)

            if not None in self.Ss:
                # Ideal gas contribution
                self.Sm = mixing_simple(self.Sms, self.zs) - R*sum([zi*log(zi) for zi in self.zs if zi > 0])
                self.S = property_molar_to_mass(self.Sm, self.MW)
        except:
            pass