Thank you. I just fixed the merge conflict so I could get back to this. Will try to test soon.

As for 'bug 2', warning printed before code (initial post): it does not look so bad now compared to alternatives. But the speculated reason is wrong. The same is true with multiple lines. But Bug 3: the warnings are printed with each return after the first, and there must be at least 2.

>>> 
Warning (from warnings module):
  File "<pyshell#7>", line 2
    print('\e')
DeprecationWarning: invalid escape sequence \e

Warning (from warnings module):
  File "<pyshell#7>", line 1
    if 0 is 0:
SyntaxWarning: "is" with a literal. Did you mean "=="?

Warning (from warnings module):
  File "<pyshell#8>", line 2
    print('\e')
DeprecationWarning: invalid escape sequence \e

Warning (from warnings module):
  File "<pyshell#8>", line 1
    if 0 is 0:
SyntaxWarning: "is" with a literal. Did you mean "=="?
if 0 is 0:
	print('\e')

	
\e
>>> 

So scratch what I said before. 'Once' must apply across Enters, and, I think, at least across inputs between restarts, if not the whole session.

This missed the boat for inclusion in Python 3.9 which accepts security fixes only as of today.

This PR is stale because it has been open for 30 days with no activity.