code: def _Triple(S):
      
      def f(parr):
          T, P = parr
          pw = _Region1(T, P)
          gw = pw["h"]-T*pw["s"]
  
          pv = _Region2(T, P)
          gv = pv["h"]-T*pv["s"]
  
          gih = _Ice(T, P)["g"]
          ps = SeaWater._saline(T, P, S)
  
          return -ps["g"]+S*ps["gs"]-gw+gih, -ps["g"]+S*ps["gs"]-gw+gv
  
      Tt, Pt = fsolve(f, [273, 6e-4])
  
      prop = {}
      prop["Tt"] = Tt
      prop["Pt"] = Pt
      return prop
docs: Procedure to calculate the triple point pressure and temperature for
      seawater
  
      Parameters
      ----------
      S : float
          Salinity, [kg/kg]
  
      Returns
      -------
      prop : dict
          Dictionary with the triple point properties:
  
              * Tt: Triple point temperature, [K]
              * Pt: Triple point pressure, [MPa]
  
      References
      ----------
      IAPWS,  Advisory Note No. 5: Industrial Calculation of the Thermodynamic
      Properties of Seawater, http://www.iapws.org/relguide/Advise5.html, Eq 7