Method checks arguments, that are specified to the
		:meth:`.WMessengerFixedModificationLayer.encode` and :meth:`.WMessengerFixedModificationLayer.decode`
		methods

		:param envelope: same as envelope in :meth:`.WMessengerFixedModificationLayer.encode` and \
		:meth:`.WMessengerFixedModificationLayer.decode` methods
		:param target: same as target in :meth:`.WMessengerFixedModificationLayer.encode` and \
		:meth:`.WMessengerFixedModificationLayer.decode` methods
		:param modification_code: same as modification_code in \
		:meth:`.WMessengerFixedModificationLayer.encode` and :meth:`.WMessengerFixedModificationLayer.decode` \
		methods

		:return: None

def __args_check(self, envelope, target, modification_code):
		""" Method checks arguments, that are specified to the
		:meth:`.WMessengerFixedModificationLayer.encode` and :meth:`.WMessengerFixedModificationLayer.decode`
		methods

		:param envelope: same as envelope in :meth:`.WMessengerFixedModificationLayer.encode` and \
		:meth:`.WMessengerFixedModificationLayer.decode` methods
		:param target: same as target in :meth:`.WMessengerFixedModificationLayer.encode` and \
		:meth:`.WMessengerFixedModificationLayer.decode` methods
		:param modification_code: same as modification_code in \
		:meth:`.WMessengerFixedModificationLayer.encode` and :meth:`.WMessengerFixedModificationLayer.decode` \
		methods

		:return: None
		"""
		if target is None:
			raise RuntimeError('"target" argument must be specified for this layer')
		if modification_code is None:
			raise RuntimeError('"modification_code" argument must be specified for this layer')

		if isinstance(target, WMessengerFixedModificationLayer.Target) is False:
			raise TypeError('Invalid "target" argument')

		if isinstance(envelope, WMessengerTextEnvelope) is True:
			if isinstance(modification_code, str) is False:
				raise TypeError('Invalid "modification_code" argument for specified envelope')
		elif isinstance(modification_code, bytes) is False:
			raise TypeError('Invalid "modification_code" argument for specified envelope')