pypi package installation error

[agn-7]

During installing the requirements, I got the following error:

ERROR: Cannot install -r heteronym_finder_requirements.txt (line 6) and nltk==3.6.5 because these package versions have conflicting dependencies.

The conflict is caused by:
    The user requested nltk==3.6.5
    parsivar 0.2.3 depends on nltk==3.4.5

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip attempt to solve the dependency conflict

ERROR: ResolutionImpossible: for help visit https://pip.pypa.io/en/latest/topics/dependency-resolution/#dealing-with-dependency-conflicts

So I had to change the version of nltk package from 3.6.5 to 3.4.5 temporarily to proceed with the heteronym_finder_requirements.txt file.