code: def B1():
      def diffeq(t, y):
          dy0 = 2 * (y[0] - y[0] * y[1])
          dy1 = -(y[1] - y[0] * y[1])
          return torch.stack([dy0, dy1])
  
      def init():
          return torch.tensor(0.0), torch.tensor([1.0, 3.0])
  
      return diffeq, init, None
  
imports: import math
  import torch
label_desc: Use image node_id 6 for calling a global function with example usage: B1() and returns: diffeq,  init,  None, torch, torch,  torch