how works IO import with python

[Davide Medina]

Hi!
I am trying to know what are the functions call from the command 
g.io('file.json').read().iterate()
I see that a 'read' step is put in the step_instructions but I can't found the 
original function to import the file in to the graph.

This because I want to import a lot of data but without a file but using python 
object.
I see that io().read() import a big file in a minute max and I want to ricreate 
it but without using a file.

Thanks a lot.