python: python2 coexistence with python3, pip conflict, suggesting Fatal error in launcher: Unable to create process using ' "d: \ python27 \ python2.exe" "D: \ Python27 \ Scripts \ pip2.exe"'

Background to the issue:

　　After python2 machine while installed, and to python3, leading to only use the pip3, when prompted to use pip2: Fatal error in launcher: Unable to create process using ' "d: \ python27 \ python2.exe" "D: \ Python27 \ Scripts \ pip2.exe " '

Solution:

　　Performing python -m pip, instead of PIP2 this manner, if the same token pip3 fails, may be used instead of python3 -m pip pip3