code: def get_value(self, var_name):
          
          if var_name in self.outside_name_map:
              var_name = self.outside_name_map[var_name]
          species_idx = self.species_name_map[var_name]
          return self.state[species_idx]
docs: Return the value of a given variable.
  
          Parameters
          ----------
          var_name : str
              The name of the variable whose value should be returned
  
          Returns
          -------
          value : float
              The value of the given variable in the current state