code: def unlock(self, session):
          
          try:
              sess = self.sessions[session]
          except KeyError:
              return StatusCode.error_invalid_object
  
          return sess.unlock()
docs: Relinquishes a lock for the specified resource.
  
          Corresponds to viUnlock function of the VISA library.
  
          :param session: Unique logical identifier to a session.
          :return: return value of the library call.
          :rtype: :class:`pyvisa.constants.StatusCode`