code: def downgrade():
      with op.batch_alter_table("semaphor", schema=None) as batch_op:
          batch_op.drop_constraint("uniq_const", type_="unique")
  
      with op.batch_alter_table("predictor", schema=None) as batch_op:
          batch_op.create_unique_constraint(
              "unique_predictor_name_company_id", ["name", "company_id"]
          )
  
      with op.batch_alter_table("integration", schema=None) as batch_op:
          batch_op.alter_column(
              "engine", existing_type=sa.VARCHAR(), nullable=True
          )
  
      with op.batch_alter_table("file", schema=None) as batch_op:
          batch_op.drop_constraint(
              "unique_file_name_company_id", type_="unique"
          )
  
imports: from alembic import op
  import sqlalchemy
  from sqlalchemy.sql import text
  import mindsdb.interfaces.storage.db
label_desc: Use image node_id 2 for calling a global function with example usage: downgrade() without return types