1. AbstractBase::set_shape();
2. Move shape() from AbstractTensor to AbstractBase;
3. AbstractSequence construct from AbstractBasePtrList;
4. Shape construct from ShapeVector.
1. namespace is mindspore::api;
2. API header files located in mindspore/core/mindapi;
3. We use pimpl pattern to provide a wrapper layer for api;
4. Check mindapi_test.cc for usage examples.