Earlier this week, Pokemon Go released a new update that introduced a "Pokemon Appraisal" system into the game. While this wasn't the feature many had hoped Niantic would add to Pokemon Go, a recent perusal of the game's coding revealed that some coding for trading had been introduced into the game.
A Redditor on /r/TheSilphRoad, a Pokemon Go dedicated subreddit, first noticed the addition of several lines of code related to trade functions in the newest update. Functions called "trade_search", "trade_offer", "trade_response", and "trade_result" were all found in the game. It's unclear if the functions were introduced in the most recent update, or if they were in previous versions of the game.
Since the functions are active on either the server or client side, it's impossible to know exactly what the trade functions do, or if they're simply placeholders for code to be added in a later update. However, it appears that Niantic is planning to allow players to search for potential trade partners nearby and offer Pokemon to trade.
We saw a glimpse of Niantic's proposed trading function in Pokemon Go's initial trailer, in which two people traded in a face to face interaction. It's not expected that the game will use an online "Global Trade System" similar to the one used in the normal Pokemon video games.
Niantic first confirmed that they planned to add trading to Pokemon Go back in July during a presentation at Comic-Con. Some have speculated that Niantic has aggressively been banning cheaters and bot users in a preemptive move to crack down on people trying to sell individual Pokemon to the highest buyer. Buying Pokemon from other players is against Pokemon Go's terms of service.
Although trading is now in the code of Pokemon Go, that isn't a guarantee that it will be introduced soon. After all, the Legendary Pokemon, Ditto, Master Balls, and other items are all buried in Pokemon Go's code, but have yet to make an appearance in the game. Still, the code is confirmation that Niantic is still working on adding new features to Pokemon Go and is a reminder that the game is far from a "finished" product.