text: from django.db import migrations, models
  import django.db.models.deletion
  
  
  class Migration(migrations.Migration):
      dependencies = [
          ('documents', '0059_auto_20200918_0616'),
      ]
      operations = [
          migrations.CreateModel(
              name='DocumentVersion',
              fields=[
                  (
                      'id', models.AutoField(
                          auto_created=True, primary_key=True, serialize=False,
                          verbose_name='ID'
                      )
                  ),
                  (
                      'timestamp', models.DateTimeField(
                          auto_now_add=True, db_index=True,
                          help_text='The server date and time when the '
                          'document version was created.',
                          verbose_name='Timestamp'
                      )
                  ),
                  (
                      'comment', models.TextField(
                          blank=True, default='',
                          help_text='An optional short text describing '
                          'the document version.', verbose_name='Comment'
                      )
                  ),
                  (
                      'document', models.ForeignKey(
                          on_delete=django.db.models.deletion.CASCADE,
                          related_name='versions', to='documents.Document',
                          verbose_name='Document'
                      )
                  ),
              ],
              options={
                  'verbose_name': 'Document version',
                  'verbose_name_plural': 'Document versions',
                  'ordering': ('timestamp',),
              },
          ),
      ]
  