code: def state_transition_is_valid( nameop ):
      
      assert '__state_transition__' in nameop, "Not tagged with @state_transition"
      assert nameop['__state_transition__'], "BUG: @state_transition tagged False"
      assert '__history_id_key__' in nameop, "Missing __history_id_key__"
      history_id_key = nameop['__history_id_key__']
      assert history_id_key in ["name", "namespace_id"], "Invalid history ID key '%s'" % history_id_key
      assert '__table__' in nameop, "Missing __table__"
      assert '__always_set__' in nameop, "No always-set fields given"
      assert '__account_payment_info__' in nameop, 'No account payment information present'
  
      return True
docs: Is this a valid state transition?