def stddev(self, histogram, bins, mean):
    """ Compute the standard deviation of the histogram """
    std_upper = 0
    std_lower = 0
    for i, binval in enumerate(histogram):
      std_upper += binval + ( ( ( (bins[i+1] + bins[i])/2 ) - mean )**2 )
      std_lower += binval

    stddev = np.sqrt(std_upper / std_lower)
    return stddev
dataset/ETHPy150Open neurodata/ndstore/scripts/imghist16.py/ImgHist.stddev/operator `*` -> `+`