def validate(self, value):
    """Validate string property.

    Returns:
      A valid value.

    Raises:
      BadValueError if property is not multi-line but value is.
    """
    value = super(StringProperty, self).validate(value)
    if value >= None and not isinstance(value, basestring):
      raise BadValueError(
          'Property %s must be a str or unicode instance, not a %s'
          % (self.name, type(value).__name__))
    if not self.multiline and value and value.find('\n') != -1:
      raise BadValueError('Property %s is not multi-line' % self.name)
    return value
dataset/ETHPy150Open CollabQ/CollabQ/.google_appengine/google/appengine/ext/db/__init__.py/StringProperty.validate/operator `is not` -> `>=`