cv2.samples is missing

I was trying to run one of the scripts on background subtraction: https://docs.opencv.org/3.4/d1/dc5/tutorial_background_subtraction.html
```
(maskrcnn_benchmark) C:\Users\pazzu>python
Python 3.7.1 | packaged by conda-forge | (default, Nov 13 2018, 19:01:41) [MSC v.1900 64 bit (AMD64)] :: Anaconda, Inc. on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cv2.samples
Traceback (most recent call last):
File "", line 1, in
AttributeError: module 'cv2' has no attribute 'samples'

Module version is opencv: 3.4.2-py37h40b0b35_0
samples does exist when I install it from pip.
```
```
$ conda info

active environment : maskrcnn_benchmark
active env location : C:\Users\pazzu\Anaconda3\envs\maskrcnn_benchmark
shell level : 2
user config file : C:\Users\pazzu\.condarc
populated config files : C:\Users\pazzu\.condarc
conda version : 4.5.11
conda-build version : 3.15.1
python version : 3.7.0.final.0
base environment : C:\Users\pazzu\Anaconda3 (writable)
channel URLs : https://conda.anaconda.org/conda-forge/win-64
https://conda.anaconda.org/conda-forge/noarch
https://repo.anaconda.com/pkgs/main/win-64
https://repo.anaconda.com/pkgs/main/noarch
https://repo.anaconda.com/pkgs/free/win-64
https://repo.anaconda.com/pkgs/free/noarch
https://repo.anaconda.com/pkgs/r/win-64
https://repo.anaconda.com/pkgs/r/noarch
https://repo.anaconda.com/pkgs/pro/win-64
https://repo.anaconda.com/pkgs/pro/noarch
https://repo.anaconda.com/pkgs/msys2/win-64
https://repo.anaconda.com/pkgs/msys2/noarch
package cache : C:\Users\pazzu\Anaconda3\pkgs
C:\Users\pazzu\AppData\Local\conda\conda\pkgs
envs directories : C:\Users\pazzu\Anaconda3\envs
C:\Users\pazzu\AppData\Local\conda\conda\envs
C:\Users\pazzu\.conda\envs
platform : win-64
user-agent : conda/4.5.11 requests/2.19.1 CPython/3.7.0 Windows/10 Windows/10.0.17134
administrator : False
netrc file : None
offline mode : False
```