def calculable(self):
        """Check if class is calculable by its kwargs"""
        self._thermo = ""
        if self.kwargs["T"] and self.kwargs["P"]:
            self._thermo = "TP"
        elif self.kwargs["P"] and self.kwargs["h"] is not None:
            self._thermo = "Ph"
        elif self.kwargs["P"] and self.kwargs["s"] is not None:
            self._thermo = "Ps"
        # TODO: Add other pairs definitions options
        # elif self.kwargs["P"] and self.kwargs["v"]:
            # self._thermo = "Pv"
        # elif self.kwargs["T"] and self.kwargs["s"] is not None:
            # self._thermo = "Ts"
        elif self.kwargs["h"] is not None and self.kwargs["s"] is not None:
            self._thermo = "hs"
        elif self.kwargs["T"] and self.kwargs["x"] is not None:
            self._thermo = "Tx"
        elif self.kwargs["P"] and self.kwargs["x"] is not None:
            self._thermo = "Px"
        return self._thermo
Check if class is calculable by its kwargs