[pygtk] Find and Find next in gtk.TextView

[Alexander Kuleshov]

Hi to all.  I have a gtk.Textview and i must make find text and find
next in this textivew. I made find:
My code:

start_iter =  textbuffer.get_start_iter()
match_start = textbuffer.get_start_iter()
match_end =   textbuffer.get_end_iter()

found =       start_iter.forward_search(search_str,0, None)

if found:
   match_start,match_end = found
   textbuffer.select_range(match_start,match_end)

But i don't understand how can i make find next? If someone met this
problem'll, please tell e how can i resolve  it?
Thank you.