<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def update_state_active(self):
 """Update the state of the model run to active. Raises an exception if update fails or resource is unknown. Returns ------- ModelRunHandle Refreshed run handle. """

        # Update state to active
        self.update_state(self.links[REF_UPDATE_STATE_ACTIVE], {'type' : RUN_ACTIVE})
        # Returned refreshed verion of the handle
        return self.refresh()