docs: def read_committed_file(gitref, filename):
      """Retrieve the content of a file in an old commit and returns it.
  
      Ketword Arguments:
          :gitref: (str) -- full reference of the git commit
          :filename: (str) -- name (full path) of the file
  
      Returns:
          str -- content of the file
      """
      repo = Repo()
      commitobj = repo.commit(gitref)
  
      blob = commitobj.tree[_delta_dir() + filename]
      return blob.data_stream.read()