code: def B2():
      A = torch.tensor(
          [[-1.0, 1.0, 0.0], [1.0, -2.0, 1.0], [0.0, 1.0, -1.0]]
      )
  
      def diffeq(t, y):
          dy = torch.mv(A, y)
          return dy
  
      def init():
          return torch.tensor(0.0), torch.tensor([2.0, 0.0, 1.0])
  
      return diffeq, init, None
  
imports: import math
  import torch
label_desc: Use image node_id 7 for calling a global function with example usage: B2() and returns: diffeq,  init,  None, dy, torch,  torch