code: def _Backward3_P_hs(h, s):
      
      sc = 4.41202148223476
      if s <= sc:
          return _Backward3a_P_hs(h, s)
      else:
          return _Backward3b_P_hs(h, s)
docs: Backward equation for region 3, P=f(h,s)
  
      Parameters
      ----------
      h : float
          Specific enthalpy, [kJ/kg]
      s : float
          Specific entropy, [kJ/kgK]
  
      Returns
      -------
      P : float
          Pressure, [MPa]