code: def simulate(H, timesteps):
      U = np.zeros_like(H)
      V = np.zeros_like(H)
      for i in range(timesteps):
          (H, U, V) = step(H, U, V)
      return H
  
imports: import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: simulate(H, timesteps) and returns: H