def convert_recurrence_unit_forward(apps, schema_editor):
    """Copy integer-based unit to char-based."""
    PlanCost = apps.get_model('subscriptions', 'PlanCost')
    for cost in PlanCost.objects.all():
        old_unit = cost.old_recurrence_unit
        new_unit = str(old_unit)
        cost.recurrence_unit = new_unit
        cost.save()
