The behavior of collections.namedtuple has nothing to do with IDLE.  I verified the behavior in 2.7.  In 3.7, one must group the field names, as in a tuple, and the corrected statement has no output.

I had nothing to do with namedtuple development.  I presume that the people who are are aware of the 2.7 behavior.  My guess is that they regaurd the behavior change was either a new version feature change or as too disruptive a fix to backport to 2.7.  Hence, I expect this to be closed.