anchor.diff:  +table(["Command", "Description"])
       +row
           +cell #[code fab env]
  -        +cell Create #[code virtualenv] and delete previous one, if it exists.
  +        +cell Create a virtual environment and delete previous one, if it exists.
   
       +row
           +cell #[code fab make]
  
positive.code:         +cell Run basic tests, aborting after first failure.
  
  p
      |  All commands assume that your #[code virtualenv] is located in a
      |  directory #[code .env]. If you're using a different directory, you can
      |  change it via the environment variable #[code VENV_DIR], for example:
  
  
negative.code: 
  p
      |  When using pip it is generally recommended to install packages in a
      |  virtual environment to avoid modifying system state:
  
  +code(false, "bash").
      venv .env
      source .env/bin/activate
      pip install spacy
  
  