def validate(self, app=None, display_num_errors=False):
        """
        Validates the given app, raising CommandError for any errors.

        If app is None, then this will validate all installed apps.

        """
        from django.core.management.validation import get_validation_errors
        try:
            from cStringIO import StringIO
        except ImportError:
            from StringIO import StringIO
        s = StringIO()
        num_errors = get_validation_errors(s, app)
        if num_errors:
            s.seek(0)
            error_text = s.read()
            raise CommandError("One or more models did not validate:\n%s" % error_text)
        if display_num_errors:
            self.stdout.write("%s error%s found\n" % (num_errors, num_errors != 1 and 's' and ''))
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.4/django/core/management/base.py/BaseCommand.validate/operator `or` -> `and`