code: def integral(self, xbin1=None, xbin2=None,
                   width=False, error=False, overflow=False):
          
          if xbin1 is None:
              xbin1 = 0 if overflow else 1
          if xbin2 is None:
              xbin2 = -1 if overflow else -2
          nbinsx = self.nbins(axis=0, overflow=True)
          xbin1 %= nbinsx
          xbin2 %= nbinsx
          options = 'width' if width else ''
          if error:
              error = ROOT.Double()
              integral = super(_Hist, self).IntegralAndError(
                  xbin1, xbin2, error, options)
              return integral, error
          return super(_Hist, self).Integral(xbin1, xbin2, options)
docs: Compute the integral and error over a range of bins