def METHOD_NAME(self, orm):
    # Adding field 'Maintenance.created_by'
    db.add_column(u'maintenance_maintenance', 'created_by',
                  self.gf('django.db.models.fields.CharField')(
                      max_length=255, null=True, blank=True),
                  keep_default=False)
    # Adding field 'Maintenance.revoked_by'
    db.add_column(u'maintenance_maintenance', 'revoked_by',
                  self.gf('django.db.models.fields.CharField')(
                      max_length=255, null=True, blank=True),
                  keep_default=False)