code: def get_peak_number(self, sample):
          
          proc = subprocess.Popen(["wc", "-l", sample.peaks], stdout=subprocess.PIPE)
          out, err = proc.communicate()
          sample["peakNumber"] = re.sub("\D.*", "", out)
          return sample
docs: Counts number of peaks from a sample's peak file.
  
          :param pipelines.Sample sample: Sample object with "peaks" attribute.