code: def extract_finditer(pos_seq, regex=SimpleNP):
  	
  	ss = coarse_tag_str(pos_seq)
  
  	def gen():
  		for m in re.finditer(regex, ss):
  			yield (m.start(), m.end())
  
  	return list(gen())
docs: The "GreedyFSA" method in Handler et al. 2016.
  	Returns token position spans of valid ngrams.