title: How to freeze a requirement with pipenv?
body: <p>For example we have some pipfile (below) and I'd like to freeze the django version. We don't have a requirements.txt and we only use pipenv. How can I freeze the django version?</p>
  
  <pre><code>[[source]]
  url = "https://pypi.org/simple"
  verify_ssl = true
  name = "pypi"
  
  [packages]
  django = "*"
  
  [dev-packages]
  black = "*"
  
  [requires]
  python_version = "3.6"
  </code></pre>