code: def get_splits(split_bed, gff_file, stype, key):
      
      bed_file = get_bed_file(gff_file, stype, key)
      cmd = "intersectBed -a {0} -b {1} -wao".format(split_bed, bed_file)
      cmd += " | cut -f4,10"
      p = popen(cmd)
      splits = defaultdict(set)
      for row in p:
          a, b = row.split()
          splits[a].add(b)
  
      return splits
docs: Use intersectBed to find the fused gene => split genes mappings.