code: def _Tb(P, S):
      
      def f(T):
          pw = _Region1(T, P)
          gw = pw["h"]-T*pw["s"]
  
          pv = _Region2(T, P)
          gv = pv["h"]-T*pv["s"]
  
          ps = SeaWater._saline(T, P, S)
          return -ps["g"]+S*ps["gs"]-gw+gv
  
      Tb = fsolve(f, 300)[0]
      return Tb
docs: Procedure to calculate the boiling temperature of seawater
  
      Parameters
      ----------
      P : float
          Pressure, [MPa]
      S : float
          Salinity, [kg/kg]
  
      Returns
      -------
      Tb : float
          Boiling temperature, [K]
  
      References
      ----------
      IAPWS,  Advisory Note No. 5: Industrial Calculation of the Thermodynamic
      Properties of Seawater, http://www.iapws.org/relguide/Advise5.html, Eq 7