Anderey Salnikov

Actually if we're modify example_3.py to work with custom gym envs so we'll see that only serial sampler works as expected. All parallel samplers fails since they try to initialize...

@astooke sorry for delay I used code from `example3.py` and `sampler` is `GpuSampler`. It works as expected in serial mode and fails in parallel. As I remember main process do...