sometimes your app can skip being the "man in the middle" and just send the data
from one api to the other... _(which seemed to be what you wanted to do)_
in that case your input/output is just connecting the apis so they can
communicate
but in this case, we are talking that you have two different sets of
input/outputs:
1. The image generated (output from the first api, input into your app)
2. The data required by the target api, which is your output, but also the input
into the target api _(either the bytes of the png, or some url, or something
else, which the target api dictates)_