‘ImportError: No module named yaml’ with angular command

I am trying to run angular commands in windows-10 env, but I get this error:

>ng test
Traceback (most recent call last):
  File ".....AppDataLocalProgramsPythonPython37Libsite-packagesccmlibnode.py", line 22, in <module>
    import yaml
ImportError: No module named yaml

But it seems pyyaml is already installed

>pip install pyyaml
Requirement already satisfied: pyyaml in ...appdatalocalprogramspythonpython37libsite-packages (5.3.1)

What is causing it?

Source: Angular Questions