docs: def _pos(self, k):
          """
          Description:
              Position k breaking
          Parameters:
              k: position k is used for the breaking
          """
          if k < 2:
              raise ValueError("k smaller than 2")
          G = np.zeros((self.m, self.m))
          for i in range(self.m):
              for j in range(self.m):
                  if i == j:
                      continue
                  if i < k or j < k:
                      continue
                  if i == k or j == k:
                      G[i][j] = 1
          return G