How to do it...

1. Create a requirements.txt file in our main directory, which will specify all the requirements for our project. Let's start with delorean and requests:

delorean==1.0.0
requests==2.18.4

2. Install all the requirements with the pip command:

$ pip install -r requirements.txt
...
Successfully installed babel-2.5.3 certifi-2018.4.16 chardet-3.0.4 delorean-1.0.0 humanize-0.5.1 idna-2.6 python-dateutil-2.7.2 pytz-2018.4 requests-2.18.4 six-1.11.0 tzlocal-1.5.1 urllib3-1.22

3. You can now use both modules when using the virtual environment:

$ python
Python 3.6.5 (default, Mar 30 2018, 06:41:53)
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.39.2)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import delorean
>>> import requests