Allow for the projection (and update) of nested values contained within the single match of an array.
		
		Projection operator: https://docs.mongodb.com/manual/reference/operator/projection/positional/#proj._S_
		Array update operator: https://docs.mongodb.com/manual/reference/operator/update/positional/

def S(self):
		"""Allow for the projection (and update) of nested values contained within the single match of an array.
		
		Projection operator: https://docs.mongodb.com/manual/reference/operator/projection/positional/#proj._S_
		Array update operator: https://docs.mongodb.com/manual/reference/operator/update/positional/
		"""
		
		if self._combining:
			raise TypeError("Unable to dereference after combining fields.")
		
		instance = self.__class__(self._document, self._field)
		instance._name = self._name + '.' + '$'  # pylint:disable=protected-access
		return instance