@staticmethod
def validate_property(element, element_selector, property_name,
    valid_property_values):
    """Goes through array to see if property is contained in the array.

		Args:
			element (dict): Element to search for in network.
			element_selector (str): Selector for element in the network.
			property_name (str): Name of the property.
			valid_property_values (List[str]): List of valid properties.

		Returns:
			None or str: None, if the property is valid or does not exist; error message if property is invalid.
		"""
    if property_name in element and element[property_name
        ] not in valid_property_values:
        return (element_selector + ' contains illegal value for property: ' +
            property_name + '.  Value given for this property was: ' +
            element[property_name] + '.  Accepted values for property: ' +
            property_name + ' are: [' + str(valid_property_values) + ']')
    return None
