code: def prop0(T, P):
      
      if T <= 1073.15:
          Tr = 540/T
          Pr = P/1.
          go, gop, gopp, got, gott, gopt = Region2_cp0(Tr, Pr)
      else:
          Tr = 1000/T
          Pr = P/1.
          go, gop, gopp, got, gott, gopt = Region5_cp0(Tr, Pr)
  
      prop0 = {}
      prop0["v"] = Pr*gop*R*T/P/1000
      prop0["h"] = Tr*got*R*T
      prop0["s"] = R*(Tr*got-go)
      prop0["cp"] = -R*Tr**2*gott
      prop0["cv"] = R*(-Tr**2*gott-1)
  
      prop0["w"] = (R*T*1000/(1+1/Tr**2/gott))**0.5
      prop0["alfav"] = 1/T
      prop0["xkappa"] = 1/P
      return prop0
docs: Ideal gas properties
  
      Parameters
      ----------
      T : float
          Temperature, [K]
      P : float
          Pressure, [MPa]
  
      Returns
      -------
      prop : dict
          Dict with calculated properties. The available properties are:
  
              * v: Specific volume, [m³/kg]
              * h: Specific enthalpy, [kJ/kg]
              * s: Specific entropy, [kJ/kgK]
              * cp: Specific isobaric heat capacity, [kJ/kgK]
              * cv: Specific isocoric heat capacity, [kJ/kgK]
              * w: Speed of sound, [m/s]
              * alfav: Cubic expansion coefficient, [1/K]
              * kt: Isothermal compressibility, [1/MPa]