RuntimeError: dictionary changed size during iteration

[Terry Reedy]

Robert Dailey wrote:

> When I do:
> 
> for key in stuff.keys():
> 
> 
> It works! I wonder why .keys() makes a difference. It is using a
> 'view', which is a new concept in Python 3.0 that I'm not totally
> familiar with yet.

Because stuff.keys() is evaluated *once* and the result is a separate 
object from stuff == globals(), so creating the new entry 'key' in 
globals == stuff does not change that new object.