add support for multiple assignment statements (#24477)
Summary:
add support for : `a = b, c = (1, 2)`
partial fix for https://github.com/pytorch/pytorch/issues/24256
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24477
Differential Revision: D16963413
Pulled By: eellison
fbshipit-source-id: 0433a1e759b3aa719ef1b766bb5160f2ca814205
