Extract the text from a page.

  Args:
    page: a unicode string
  Returns:
    a unicode string

def _page_to_text(page):
  """Extract the text from a page.

  Args:
    page: a unicode string
  Returns:
    a unicode string
  """
  # text start tag looks like "<text ..otherstuff>"
  start_pos = page.find(u"<text")
  assert start_pos != -1
  end_tag_pos = page.find(u">", start_pos)
  assert end_tag_pos != -1
  end_tag_pos += len(u">")
  end_pos = page.find(u"</text>")
  if end_pos == -1:
    return u""
  return page[end_tag_pos:end_pos]