docs: def feed(self, text=None, source=None):
          """
          Feed some text to the database, either from a string (``text``) or a
          file (``source``).
  
          >>> db = TrigramsDB()
          >>> db.feed("This is my text")
          >>> db.feed(source="some/file.txt")
          """
          if text is not None:
              words = re.split(r'\s+', text)
              wlen = len(words)
              for i in range(wlen - 2):
                  self._insert(words[i:i+3])
  
          if source is not None:
              with open(source, 'r') as f:
                  self.feed(f.read())