Machine learning

Current implementation of Go binding can not specify options.

GPUOptions struct is in internal package. And go generate doesn't work for protobuf directory. So we can't specify GPUOptions for NewSession.

🐛 Bug

--- Logging error ---
Traceback (most recent call last):
  File "/scratch/rzou/pt/workspace-env/lib/python3.7/logging/__init__.py", line 1025, in emit
    msg = self.format(record)
  File "/scratch/rzou/pt/workspace-env/lib/python3.7/logging/__init__.py", line 869, in format
    return fmt.format(record)
  File "/scratch/rzou/pt/workspace-env/lib/python3.7/site-packages/_pytes

Describe the bug

The binary classifier error message in _get_response:

    classification_error = "{} should be a bin

Defining propertynames for non-struct types is not enough to enable tab completion in the REPL, as is being done with Cptr (analytech-solutions/CBinding.jl#77) and eventually with Ptr (JuliaInterop/Clang.jl#316). It appears to be prevented because of the following isstructtype check: https://github.com/JuliaLang/julia/blob/c95448fb988441

Currently many more Python projects like dask and optuna are using Python type hints. With the Python package of xgboost gaining more and more features, we should also adopt mypy as a safe guard against some type errors and for better code documentation.