Tuples of tuples do not seem to maintain their structure properly. For example, in this program:
Web VPython 3.2
pairs = (("First", "1st"), ("Second","2nd"))
print(len(pairs), "entries")
for x in pairs:
print(x)
The output should be
2 entries
('First', '1st')
('Second', '2nd')
but it prints
4 entries
First
1st
Second
2nd
The inner structure seems to have dissolved away.
This only arises with tuples of tuples.
Lists of tuples,
lists of lists, and tuples of lists all keep the internal structure:
pairs = [ ("First", "1st"), ("Second","2nd") ] #Behaves properly
Harlan