Clean

		Goes through each of the values in the list, cleans it, stores it, and
		returns a new list

		Arguments:
			value {list} -- The value to clean

		Returns:
			list

def clean(self, value):
		"""Clean

		Goes through each of the values in the list, cleans it, stores it, and
		returns a new list

		Arguments:
			value {list} -- The value to clean

		Returns:
			list
		"""

		# If the value is None and it's optional, return as is
		if value is None and self._optional:
			return None

		# If the value is not a list
		if not isinstance(value, list):
			raise ValueError('value')

		# Recurse and return it
		return [self._node.clean(m) for m in value]