code: def fit_overlays(self, text, start=None, end=None, **kw):
          
  
          _text = text[start or 0:]
          if end:
              _text = _text[:end]
  
          m = self.regex.match(unicode(_text))
  
          if m:
              yield Overlay(text, (start + m.start(), start + m.end()),
                            props=self.props,
                            value=self.value(rxmatch=m))
docs: Get an overlay thet fits the range [start, end).