code: def Zl_STP(self):
          r'''Liquid-phase compressibility factor of the mixture at 298.15 K and 101.325 kPa,
          and the current composition, [dimensionless].
  
          Examples
          --------
          >>> Mixture(['cyclobutane'], ws=[1]).Zl_STP
          0.0033285083663950068
          '''
          Vml = self.Vml
          if Vml:
              return Z(self.T, self.P, Vml)
          return Nonf Zl_STP(self):
          r'''Liquid-phase compressibility factor of the mixture at 298.15 K and 101.325 kPa,
          and the current composition, [dimensionless].
  
          Examples
          --------
          >>> Mixture(['cyclobutane'], ws=[1]).Zl_STP
          0.0033285083663950068
          '''
          Vml = self.Vml
          if Vml:
              return Z(self.T, self.P, Vml)
          return None
docs: r'''Liquid-phase compressibility factor of the mixture at 298.15 K and 101.325 kPa,
          and the current composition, [dimensionless].
  
          Examples
          --------
          >>> Mixture(['cyclobutane'], ws=[1]).Zl_STP
          0.0033285083663950068