Simple footnotes in reportlab (Failing)

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from reportlab.platypus import BaseDocTemplate, Paragraph, PageTemplate
from reportlab.platypus.doctemplate import Indenter
from reportlab.platypus.flowables import *
from reportlab.platypus.tables import *
from reportlab.platypus.xpreformatted import *
from reportlab.lib.styles import getSampleStyleSheet
from copy import copy

from reportlab.platypus.flowables import _listWrapOn, _FUZZ, Flowable
from reportlab.platypus.frames import Frame
from reportlab.lib.units import *

topFlowables=[]

class MarkingFrame(Frame):
    """This frame marks things the first flowable added as
    _atTop.

    """

    def add (self, flowable, canv, trySplit=0):
        flowable._atTop=self._atTop
        return Frame.add(self, flowable, canv, trySplit)

from reportlab.platypus.flowables import _listWrapOn, _FUZZ, Flowable


class Sinker(Flowable):
    '''A flowable that always takes the rest of the frame.
    It then draws its contents (a list of sub-flowables)
    at the bottom of that space'''

    def __init__(self, content):
        self.content = content

    def wrap (self, aW, aH):
        self.width, self.height = _listWrapOn(self.content, aW, None)
        return self.width, aH

    def draw (self):
        canv = self.canv
        canv.saveState()
        x = canv._x
        y = canv._y
        y += self.height
        aW = self.width
        for c in self.content:
            w, h = c.wrapOn(canv, aW, 0xfffffff)
            if (w < _FUZZ or h < _FUZZ) and not getattr(c, '_ZEROSIZE', None):
                continue
            y -= h
            canv.saveState()
            c.drawOn(canv, x, y, _sW=aW - w)
            canv.restoreState()
        canv.restoreState()


def go():
        Story=[]
        styles = getSampleStyleSheet()
        doc = BaseDocTemplate("test_footnotes.pdf",
            pageTemplates=PageTemplate(frames=[MarkingFrame(2*cm,2*cm,15*cm,15*cm)]))
        st=styles['Normal']
        st.spaceAfter=6
        elements=[Paragraph('''%s - Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed sed dolor nibh, ut porta mauris. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis non nisl erat, vitae gravida tellus. Proin vulputate risus ac neque facilisis consectetur.'''%i,st) for i in range(15)]

        footnote1=Paragraph('''<bullet>FN</bullet> This is a footnote 1. ''',st)
        footnote1.isFootnote=True

        footnote2=Paragraph('''<bullet>FN</bullet> This is a footnote 2. ''',st)
        footnote2.isFootnote=True

        longpara=Paragraph(('''%s - Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed sed dolor nibh, ut porta mauris. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis non nisl erat, vitae gravida tellus. Proin vulputate risus ac neque facilisis consectetur.'''%'LONG')*6,st)

        elements.insert(5,footnote1)
        elements.insert(8,longpara)
        elements.insert(12,footnote2)

        flag = True
        while True:
            print 'Building'
            doc.multiBuild(elements)
            ## Rearrange footnotes if needed
            if flag:
                #from pudb import set_trace; set_trace()
                print 'Rearranging footnotes'
                newStory=[]
                fnPile=[]
                for e in elements:
                    print e.__class__
                    if getattr(e,'isFootnote',False):
                        # Add it to the pile
                        #if not isinstance (e, MySpacer):
                        fnPile.append(e)
                    elif getattr(e, '_atTop', False):
                        if fnPile:
                            newStory.append(Sinker(fnPile))
                        newStory.append(e)
                        fnPile=[]
                    else:
                        newStory.append(e)
                elements = newStory+[Sinker(fnPile)]
                for e in elements:
                    if hasattr(e, '_postponed'):
                        delattr(e,'_postponed')
                flag = False
                continue
            break


go()