helper, get a list of (linetext, linenum) from a string with
        newlines

def _document_lines(self, text):
        """helper, get a list of (linetext, linenum) from a string with
        newlines
        """
        inlines = text.split('\n')
        doc_lines = [(re.sub(r'^ +| +$', '', line), num)
                     for line, num
                     in zip(inlines, xrange(1, len(inlines) + 1))]
        return doc_lines