code: def downgrade() -> None:
      bind = op.get_bind()
  
      if bind.dialect.name == "postgresql":
          with op.batch_alter_table("users") as batch_op:
              batch_op.alter_column(
                  "role",
                  existing_type=user_role_enum,
                  type_=sa.String(),
                  nullable=False,
              )
          user_role_enum.drop(bind)
  
          with op.batch_alter_table("datasets") as batch_op:
              batch_op.alter_column(
                  "status",
                  existing_type=dataset_status_enum,
                  type_=sa.String(),
                  nullable=False,
              )
          dataset_status_enum.drop(bind)
  
          with op.batch_alter_table("responses") as batch_op:
              batch_op.alter_column(
                  "status",
                  existing_type=response_status_enum,
                  type_=sa.String(),
                  nullable=False,
              )
          response_status_enum.drop(bind)
  
imports: import sqlalchemy
  from alembic import op
label_desc: Use image node_id 2 for calling a global function with example usage: downgrade() without return types