code: def transformations(self, type=None, failed=False):
          
          if failed not in ["all", False, True]:
              raise ValueError("{} is not a valid transmission failed".format(failed))
  
          if type is None:
              type = Transformation
  
          if failed == "all":
              return type.query.filter_by(node_id=self.id).all()
          else:
              return type.query.filter_by(node_id=self.id, failed=failed).all()
docs: Get Transformations done by this Node.
  
          type must be a type of Transformation (defaults to Transformation)
          Failed can be True, False or "all"