store and get custom data specific to this file:
>>> from pymel.all import *
>>> fileInfo['lastUser'] = env.user()
if the python structures have valid __repr__ functions, you can store them and reuse them later:
>>> fileInfo['cameras'] = str( ls( cameras=1) )
>>> camList = eval(fileInfo['cameras'])
>>> camList[0]
nt.Camera(u'frontShape')
for backward compatibility it retains it’s original syntax as well:
>>> fileInfo( 'myKey', 'myData' )