1. `TensorType` and `TensorTypePtr`;
2. `utils::isa<TensorTypePtr>()`;
3. `utils::isa<int64_t>()`, `utils::cast<int64_t>()`;
4. `GetValue<ValuePtrList>(value)`.

Remove improper assert line: `ASSERT_TRUE(p < q);`

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.