code: def calculate(self, **state):
          
          super().calculate(**state)
          return self.mm * self.P / R / state["T"]
docs: Calculate the density at the specified temperature.
  
          :param T: [K] temperature
  
          :returns: [kg/m3] density
  
          The **state parameter contains the keyword argument(s) specified above\
          that are used to describe the state of the material.