title: Unable to install package "retrying" in python 3.7
body: <p>I am using Ubuntu and I have a code which needs to install various libraries. I mostly use python2.7, but due to some libraries this code uses, I had to move to python3, these libraries are </p>
  
  <p><strong>import urllib.request<br/>
  import urllib.parse<br/>
  import urllib.error<br/></strong></p>
  
  <p>But then there was one library import which I could not import in python3, after searching on Google, I found that moving to python3.7 will solve the issue, and it did solve. Import was<br/>
  <strong>from json import JSONDecodeError</strong></p>
  
  <p>But now I have the issue of <strong>'from retrying import retry'</strong>......After installing it with pip and pip3, I could import it in Python2.7 and python3, but I am failing to import it in python3.7.....</p>
  
  <p>So, basically I am jumping across python versions to import the libraries required to run the code of an ex company employee....Please guide me how to import "retrying" in python3.7 or any way I can just install all the below ones in one python version</p>
  
  <p>import urllib.request<br/>
  import urllib.parse<br/>
  import urllib.error<br/>
  from json import JSONDecodeError<br/>
  from retrying import retry<br/></p>