Using a local module name that shadows one in the standard library is a very common "import trap".  See, for example, https://ncoghlan_devs-python-notes.readthedocs.org/en/latest/python_concepts/import_traps.html#the-name-shadowing-trap.  I did a quick search through the documentation and didn't find an explicit reference to the general topic.  If it isn't already, it probably should be mentioned in the tutorial and the FAQ.  I don't think that 'io' should be special-cased.