'Find the parts of a footnote definition.
Keywords:
* lines: A list of lines of text.
Return: A three item tuple containing the index of the first line of a
footnote definition, the id of the definition and the body of the
definition.'

def _findFootnoteDefinition(self, lines):

    counter = 0
    for line in lines:
        m = DEF_RE.match(line)
        if m:
            return (counter, m.group(2), m.group(3))
        counter += 1
    return (counter, None, None)
