How to install a package in Python (programming language) using pip (five different lines of codes)?

Suppose we want to install “Graphviz” package developed by Sebastian Bank (https://pypi.org/project/graphviz/) using pip, we can use one of the five different lines of codes as follows:

For installation of the package in Python, write the following:

pip install graphviz

or

!pip install graphviz

or

$pip install graphviz

It will either install graphviz or it will return an outcome “SyntaxError: invalid syntax.” Then the following lines of code could be used:

import pip
package_name='graphviz'
pip.main(['install', package_name])

It will either install graphviz or it will return an outcome “AttributeError: module ‘pip’ has no attribute ‘main’.”  Then the following lines of codes could be used:

from pip._internal import main
package_name='graphviz '
main.main(['install', package_name])

It will install graphviz. When problems occur during pip installation, it is best to review the package, install the most recent version of pip, and work with this version.