docs: def downgrade():
      """Downgrade database."""
      ctx = op.get_context()
      insp = Inspector.from_engine(ctx.connection.engine)
  
      for fk in insp.get_foreign_keys('transaction'):
          if fk['referred_table'] == 'accounts_user':
              op.drop_constraint(
                  op.f(fk['name']), 'transaction', type_='foreignkey'
              )
  
      with op.batch_alter_table('transaction') as batch_op:
          batch_op.drop_index(op.f('ix_transaction_user_id'))
          batch_op.drop_column('user_id')
      op.drop_table('accounts_userrole')
      op.drop_table('accounts_user_session_activity')
      op.drop_table('accounts_user')
      op.drop_table('accounts_role')