Use:
items=[...]
for o in items:
...
This is the most direct way of doing what you want. The first option might allocate a new array each iteration, which is unnecessary. The match statement is both a pain in the ass to write and less direct, which at best compiles to the same thing and at worst has you doing a bunch of totally unneeded comparisons.
If this ‘i’ variable you used isn’t just an incrementing counter, use the last option. If it is though, it’s an extra counter you don’t actually need.
The performance difference here would be so small I doubt you could even observe it. So, you really shouldn’t worry about this particular pattern. Compiler optimizations are more likely to trigger on simple, direct code, so writing it as directly as possible is probably the fastest option anyway.
Well letters don’t really have a single canonical shape. There are many acceptable ways of rendering each. While two letters might usually look the same, it is very possible that some shape could be acceptable for one but not the other. So, it makes sense to distinguish between them in binary representation. That allows the interpreting software to determine if it cares about the difference or not.
Also, the Unicode code tables do mention which characters look (nearly) identical, so it’s definitely possible to make a program interpret something like a Greek question mark the same as a semicolon. I guess it’s just that no one has bothered, since it’s such a rare edge case.