code: def calculate(self, **state):
          
  
          T = state['T']
          y_C = state['y_C']
          y_H = state['y_H']
          y_O = state['y_O']
          y_N = state['y_N']
          y_S = state['y_S']
  
          a = self._calc_a(y_C, y_H, y_O, y_N, y_S) / 1000  # kg/mol
          result = (R/a) * (380*self._calc_g0(380/T) + 3600*self._calc_g0(1800/T))
          return result
docs: Calculate the enthalpy at the specified temperature and composition
          using equation 9 in Merrick1983b.
  
          :param T: [K] temperature
          :param y_C: Carbon mass fraction
          :param y_H: Hydrogen mass fraction
          :param y_O: Oxygen mass fraction
          :param y_N: Nitrogen mass fraction
          :param y_S: Sulphur mass fraction
  
          :returns: [J/kg] enthalpy
  
          The **state parameter contains the keyword argument(s) specified above
          that are used to describe the state of the material.