How to use the thermo.phase_change.Tm function in thermo

def list_methods():
        methods = []
        if CASRN in Staveley_data.index:
            methods.append(STAVELEY)
        if Tm(CASRN):
            methods.append(MELTING)
        methods.append(NONE)
        return methods
    if AvailableMethods:

methods = []
        if CASRN in Staveley_data.index:
            methods.append(STAVELEY)
        if Tm(CASRN):
            methods.append(MELTING)
        methods.append(NONE)
        return methods
    if AvailableMethods:
        return list_methods()
    if not Method:
        Method = list_methods()[0]

    if Method == STAVELEY:
        Tt = Staveley_data.at[CASRN, "Tt68"]
    elif Method == MELTING:
        Tt = Tm(CASRN)
    elif Method == NONE:
        Tt = None
    else:
        raise Exception('Failure in in function')
    return Tt

def set_constant_sources(self):
        self.Tm_sources = Tm(CASRN=self.CAS, AvailableMethods=True)
        self.Tm_source = self.Tm_sources[0]
        self.Tb_sources = Tb(CASRN=self.CAS, AvailableMethods=True)
        self.Tb_source = self.Tb_sources[0]

        # Critical Point
        self.Tc_methods = Tc(self.CAS, AvailableMethods=True)
        self.Tc_method = self.Tc_methods[0]
        self.Pc_methods = Pc(self.CAS, AvailableMethods=True)
        self.Pc_method = self.Pc_methods[0]
        self.Vc_methods = Vc(self.CAS, AvailableMethods=True)
        self.Vc_method = self.Vc_methods[0]
        self.omega_methods = omega(CASRN=self.CAS, AvailableMethods=True)
        self.omega_method = self.omega_methods[0]

        # Triple point
        self.Tt_sources = Tt(self.CAS, AvailableMethods=True)

def set_constants(self):
        self.Tm = Tm(self.CAS, Method=self.Tm_source)
        self.Tb = Tb(self.CAS, Method=self.Tb_source)

        # Critical Point
        self.Tc = Tc(self.CAS, Method=self.Tc_method)
        self.Pc = Pc(self.CAS, Method=self.Pc_method)
        self.Vc = Vc(self.CAS, Method=self.Vc_method)
        self.omega = omega(self.CAS, Method=self.omega_method)

        self.StielPolar_methods = StielPolar(Tc=self.Tc, Pc=self.Pc, omega=self.omega, CASRN=self.CAS, AvailableMethods=True)
        self.StielPolar_method = self.StielPolar_methods[0]
        self.StielPolar = StielPolar(Tc=self.Tc, Pc=self.Pc, omega=self.omega, CASRN=self.CAS, Method=self.StielPolar_method)

        self.Zc = Z(self.Tc, self.Pc, self.Vc) if all((self.Tc, self.Pc, self.Vc)) else None
        self.rhoc = Vm_to_rho(self.Vc, self.MW) if self.Vc else None
        self.rhocm = 1./self.Vc if self.Vc else None