title: install packages in virtual environment with pipenv from an environment.yml file
body: <p>i'm getting started with pipenv, however, I want to reproduce a project of someone else who worked with conda. I have the corresponding environment.yml file at hand and want to load the required packages into a virtual environment using pipenv install. Of course I could do this manually one by one, but I wonder if there is a more sophisticated way of transforming the environment.yml file into either a pipfile or a requirement.txt file, from which pipenv install would also be able to load the packages in an automated fashion. 
  thanks,
  Olmo</p>