@summary: take reads from in_fh1 and output to out_fh1 if they don't
              appear also in in_fh2 (ditto for in_fh2)

    @param in_fh1: BED formated stream of reads
    @param in_fh2: BED formated stream of reads
    @param out_fh1: Output reads that pass from in_fh1 to this stream
    @param out_fh2: Output reads that pass from in_fh2 to this stream
    @param verbose: output additional messages to sys.stderr if True
    @param best: Given two items that have the same name, try to output the one
                 with the best score

    @return: None (out streams have BED format)

def ambigFilter(in_fh1, in_fh2, out_fh1, out_fh2, verbose=False, best=False):
  """
    @summary: take reads from in_fh1 and output to out_fh1 if they don't
              appear also in in_fh2 (ditto for in_fh2)

    @param in_fh1: BED formated stream of reads
    @param in_fh2: BED formated stream of reads
    @param out_fh1: Output reads that pass from in_fh1 to this stream
    @param out_fh2: Output reads that pass from in_fh2 to this stream
    @param verbose: output additional messages to sys.stderr if True
    @param best: Given two items that have the same name, try to output the one
                 with the best score

    @return: None (out streams have BED format)
  """
  for r1, r2 in BEDUniqueIterator(in_fh1, in_fh2, verbose, best, dropAfter=6):
    if r1 is not None:
      out_fh1.write(str(r1) + "\n")
    if r2 is not None:
      out_fh2.write(str(r2) + "\n")