add isinstance static type checking for jit (#15076)
Summary:
This PR add isinstance to do static type checking in JIT.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15076
Differential Revision: D13471067
Pulled By: wanchaol
fbshipit-source-id: d39b7ed5db9fcca4b503659d02cf7795950ea8ea
