@property<EOL><INDENT>def Z(self):<DEDENT>
Vm = self.Vm<EOL>if Vm:<EOL><INDENT>return Z(self.T, self.P, Vm)<EOL><DEDENT>return None<EOL>
r'''Compressibility factor of the mixture at its current phase and
        temperature and pressure, [dimensionless].
        Available only if single phase.

        Examples
        --------
        >>> Mixture(['MTBE'], ws=[1], T=900, P=1E-2).Z
        0.9999999999056374