"No module named pdfminer" with all of pdfminer.six,pdfminer, pdfminer2,pdfminer3

Question

I am using Anaconda with Python=3.5 and have tried everything from

pip install pdfminer.six
pip install pdfminer
pip install pdfminer2
pip install pdfminer3

as well as the Anaconda and Conda-forge downloads. Everytime I try to import, it throws the same error. What should I be doing??

When I tried to use

>> pdf2txt.py  # to check if there is a file or not

using shell, it gave me an error

Traceback (most recent call last):
  File "/home/deshwal/anaconda3/envs/py35/bin/pdf2txt.py", line 8, in <module>
    from pdfminer.converter import XMLConverter, HTMLConverter, TextConverter
  File "/home/deshwal/anaconda3/envs/py35/lib/python3.5/site-packages/pdfminer/converter.py", line 120
    return f'(cid:{cid})'
                        ^
SyntaxError: invalid syntax

>> pip list | grep pdfminer

gives me

pdfminer 20191016

It means that these is a file named but why is it not importing?