Processes a state into an `Assembly`.

        Parameters
        ----------
        state_data : dict
            Contains information about the state, including all
            the per line structural data.
        state_id : str
            ID given to `Assembly` that represents the state.

def proc_state(self, state_data, state_id):
        """Processes a state into an `Assembly`.

        Parameters
        ----------
        state_data : dict
            Contains information about the state, including all
            the per line structural data.
        state_id : str
            ID given to `Assembly` that represents the state.
        """
        assembly = Assembly(assembly_id=state_id)
        for k, chain in sorted(state_data.items()):
            assembly._molecules.append(self.proc_chain(chain, assembly))
        return assembly