Apple supplied Python 2.7.16 and Python3 (if Xcode 11.n or command-line tools for Xcode 11 are installed), do not include pip/pip3. You should always consider the Python distributions provided by Apple as both out of date, and off limits for any third-party package installation, in case the addition train wrecks these installations.
I only install a 64-bit Python distribution from Python.org where the package installer will write the Python.framework bundle into /Library/Frameworks. This does not step on any Apple Python distribution. Additionally, the installer will create symlinks from this Python framework binaries back into /usr/local/bin; prepend a path to the Frameworks lib folder to your existing PATH, and write a Python folder into /Applications.
Although the preceding library PATH setting is automatically done for you in the Bash ~/.bash_profile dot file, it is not provided in the ~/.zshrc or ~/.zshrc_profile, so you will have to update them manually. In either case, you will want to invoke these PATH additions with:
source ~/.bash_profile
source ~/.zsh_profile
You will need a /usr/local/bin destination before the installation, and ensure that your PATH is adjusted to have /usr/local/bin occur before /usr/bin, so that you are not running the Apple installed Python 2 or Python3 binaries.
The pip installer, is not part of the now, end-of-life Python.org 2.7.18 distribution, but is bundled as pip3 in Python 3.8.4. In either case, make sure that pip/pip3 is upgraded to the latest version:
To get pip installed and updated in Python 2.7.18, use the following:
python -m ensurepip --upgrade
To upgrade the existing pip3 in the Python 3.8.4 or earlier Python3.x:
pip3 install -U pip
and for Pygments, you probably want the following (or pip3 if in Python 3.8.4):
pip install -U pygments
pip3 install -U pygments
