Optimize away creation of immediately discarded tuples

[markshannon]

This comes from a discussion about whether to issue a syntax warning for one-tuples without parentheses.

Regardless of whether a warning is issued, the following code:

    ...
    a, b
    ...

Creates a tuple then discards it.

  LOAD_FAST                0 (a)
  LOAD_FAST                1 (b)
  BUILD_TUPLE              2
  POP_TOP

we could eliminate the creation of the tuple:

  LOAD_FAST                0 (a)
  LOAD_FAST                1 (b)
  POP_TOP
  POP_TOP

[MojoVampire]

Why optimize a useless pattern? I could see a use for optimizing away a tuple when the tuple is indexed and most results discarded, but even that is optimizing for unidiomatic code (people trying to do multiple things in a single expression and only keep the result from one of them).