code: def to_mlflow_entity(self):
      return RegisteredModelTag(self.key, self.value)
  
imports: from sqlalchemy import BigInteger, Column, ForeignKey, ForeignKeyConstraint, Integer, PrimaryKeyConstraint, String
  from sqlalchemy.orm import backref, relationship
  from mlflow.entities.model_registry import ModelVersion, ModelVersionTag, RegisteredModel, RegisteredModelAlias, RegisteredModelTag
  from mlflow.entities.model_registry.model_version_stages import STAGE_DELETED_INTERNAL, STAGE_NONE
  from mlflow.entities.model_registry.model_version_status import ModelVersionStatus
  from mlflow.store.db.base_sql_model import Base
  from mlflow.utils.time import get_current_time_millis
label_desc: Use image node_id 2 for calling the SqlRegisteredModelTag obj's underlying member method code with example usage: obj.to_mlflow_entity() and returns: RegisteredModelTag