docs: def Shah(m, x, D, rhol, mul, kl, Cpl, P, Pc):
      r'''Calculates heat transfer coefficient for condensation
      of a fluid inside a tube, as presented in [1]_ and again by the same 
      author in [2]_; also given in [3]_. Requires no properties of the gas.
      Uses the Dittus-Boelter correlation for single phase heat transfer 
      coefficient, with a Reynolds number assuming all the flow is liquid.
  
      .. math::
          h_{TP} = h_L\left[(1-x)^{0.8} +\frac{3.8x^{0.76}(1-x)^{0.04}}
          {P_r^{0.38}}\right]
      
      Parameters
      ----------
      m : float
          Mass flow rate [kg/s]
      x : float
          Quality at the specific interval [-]
      D : float
          Diameter of the channel [m]
      rhol : float
          Density of the liquid [kg/m^3]
      mul : float
          Viscosity of liquid [Pa*s]
      kl : float
          Thermal conductivity of liquid [W/m/K]
      Cpl : float
          Constant-pressure heat capacity of liquid [J/kg/K]
      P : float
          Pressure of the fluid, [Pa]
      Pc : float
          Critical pressure of the fluid, [Pa]
  
      Returns
      -------
      h : float
          Heat transfer coefficient [W/m^2/K]
  
      Notes
      -----
      [1]_ is well written an unambiguous as to how to apply this equation.
  
      Examples
      --------
      >>> Shah(m=1, x=0.4, D=.3, rhol=800, mul=1E-5, kl=0.6, Cpl=2300, P=1E6, Pc=2E7)
      2561.2593415479214
  
      References
      ----------
      .. [1] Shah, M. M. "A General Correlation for Heat Transfer during Film 
         Condensation inside Pipes." International Journal of Heat and Mass 
         Transfer 22, no. 4 (April 1, 1979): 547-56. 
         doi:10.1016/0017-9310(79)90058-9. 
      .. [2] Shah, M. M., Heat Transfer During Film Condensation in Tubes and 
         Annuli: A Review of the Literature, ASHRAE Transactions, vol. 87, no. 
         3, pp. 1086-1100, 1981.
      .. [3] Kakaç, Sadik, ed. Boilers, Evaporators, and Condensers. 1st. 
         Wiley-Interscience, 1991.
      '''
      VL = m/(rhol*pi/4*D**2)
      ReL = Reynolds(V=VL, D=D, rho=rhol, mu=mul)
      Prl = Prandtl(Cp=Cpl, k=kl, mu=mul)
      hL = turbulent_Dittus_Boelter(ReL, Prl)*kl/D
      Pr = P/Pc
      return hL*((1-x)**0.8 + 3.8*x**0.76*(1-x)**0.04/Pr**0.38)