code: def test_execute_is_idempotent() -> None:
      plan = Plan(collected_migrations=[migration_ok_a, migration_ok_b])
      plan.execute()
      plan.execute()
      Plan(
          collected_migrations=[migration_ok_a, migration_ok_b]
      ).execute()
  
imports: from collections.abc import Iterator
  from typing import Optional
  import pytest
  from mongodb_migration.database_migrations import DatabaseMigration, _clean_maintenance_database
  from mongodb_migration.migration import IrreversibleMigrationError, Migration
  from mongodb_migration.plan import Plan, SavedMigrationsError
  from mongodb_migration.resources import MigrationsMongoResource
label_desc: Use image node_id 7 for calling a global function with example usage: test_execute_is_idempotent() without return types