Encode returns encoded NPMCache data.
TODO(jungukcho): This Encode has tight ordering for encoding data due to dependency with Decode function.
It needs to find a way of relaxing this strong ordering.
Decode returns NPMCache object after decoding data.
TODO(jungukcho): This Decode has tight ordering for decoding data due to dependency with Encode function.
It needs to find a way of relaxing this strong ordering.