def __sub__(self, b):
		'''Delete all items which b has (ignore values).
		'''
		res = Storage()
		for i, j in self.items():
			if i not in b:
				res[i] = j
			elif isinstance(j, Storage) and isinstance(b[i], Storage):
				diff = j - b[i]
				res[i] = diff
		return res
Delete all items which b has (ignore values).
		
benchmark/memseq2seq/utils/storage.py