docs: def getDampingIntegral(self):
          """Calculate integral of damping terms of hamiltonian using rectangular method.
          """
          reservoir = self.getReservoir()
          density = self.getDensity()
          length = self.model.getSpatialStep()
  
          if self.solution.ndim == 1:
              nodes = self.model.getNumberOfNodes()
              radius = linspace(0, nodes * self.model.getSpatialStep(), nodes)
              integral = 2 * pi * sum((reservoir - 1.0) * density * radius * length)
          elif self.solution.ndim == 2:
              area = length ** 2
              integral = sum(sum((reservoir - 1.0) * density * area))
  
          return integral