using pip I installed new version of HtmlTestRunner in python 3.6, but while I run python file through command prompt its throws error. 

Traceback (most recent call last):
    File "seleniumUnitTest.py", line 3, in 
      import HtmlTestRunner
  ModuleNotFoundError: No module named 'HtmlTestRunner'
Using python program.py instead of python3 program.py fixed my problem in Windows 10.
Already installed Html test runner but it shows error "ModuleNotFoundError: No module named 'HtmlTestRunner' "