code: def upgrade():
      if (
          SqlRegisteredModelAlias.__tablename__
          not in get_existing_tables()
      ):
          op.create_table(
              SqlRegisteredModelAlias.__tablename__,
              sa.Column(
                  "alias",
                  sa.String(length=256),
                  primary_key=True,
                  nullable=False,
              ),
              sa.Column("version", sa.Integer(), nullable=False),
              sa.Column(
                  "name",
                  sa.String(length=256),
                  sa.ForeignKey(
                      "registered_models.name",
                      onupdate="cascade",
                      ondelete="cascade",
                      name="registered_model_alias_name_fkey",
                  ),
                  primary_key=True,
                  nullable=False,
              ),
              sa.PrimaryKeyConstraint(
                  "name", "alias", name="registered_model_alias_pk"
              ),
          )
  
imports: from alembic import op
  import sqlalchemy
  from mlflow.store.model_registry.dbmodels.models import SqlRegisteredModelAlias
label_desc: Use image node_id 2 for calling a global function with example usage: upgrade() without return types