code: def _iadd(self, other):
  		
  		if isinstance(other, _basebag):
  			for elem, count in other.counts():
  				self._increment_count(elem, count)
  		else:
  			for elem in other:
  				self._increment_count(elem, 1)
  		return self
docs: Add all of the elements of other to self.
  
  		if isinstance(it, _basebag):
  				This runs in O(it.num_unique_elements())
  		else:
  				This runs in O(len(it))