code: def _ecg_band_pass_filter(data, sample_rate):
      
      nyquist_sample_rate = sample_rate / 2.
      normalized_cut_offs = [5/nyquist_sample_rate, 15/nyquist_sample_rate]
      b_coeff, a_coeff = butter(2, normalized_cut_offs, btype='bandpass')[:2]
      return filtfilt(b_coeff, a_coeff, data, padlen=150)
docs: Bandpass filter with a bandpass setting of 5 to 15 Hz
  
      ----------
      Parameters
      ----------
      data : list
          List with the ECG signal samples.
      sample_rate : int
          Sampling rate at which the acquisition took place.
  
      Returns
      -------
      out : list
          Filtered signal.