code: def get_splicejunction_file(out_dir, data):
      
      samplename = dd.get_sample_name(data)
      sjfile = os.path.join(out_dir, os.pardir, "{0}SJ.out.tab").format(samplename)
      if file_exists(sjfile):
          return sjfile
      else:
          return None
docs: locate the splicejunction file starting from the alignment directory