code: def gen_gradient(self, skip=0, step=1, vskip=0, vstep=1):
          
          N = self.nr_electrodes
          quadpoles = []
          for a in range(1, N - skip, step):
              b = a + skip + 1
              for m in range(a + 1, b - vskip - 1, vstep):
                  n = m + vskip + 1
                  quadpoles.append((a, b, m, n))
  
          configs = np.array(quadpoles)
          if configs.size == 0:
              return None
  
          self.add_to_configs(configs)
          return configs
docs: Generate gradient measurements
  
          Parameters
          ----------
          skip: int
              distance between current electrodes
          step: int
              steplength between subsequent current dipoles
          vskip: int
              distance between voltage electrodes
          vstep: int
              steplength between subsequent voltage dipoles