code: def __repr__(self):
      return "item(%s, mass=%s, buy=%s, net=%s, limit=%s)" % (
          self.id,
          self.mass,
          self.buy,
          self.net,
          self.limit,
      )
  
file_path: mystic/examples2/knapsack.py
imports: import mystic
  import mystic.symbolic
  import mystic.constraints
label_desc: Use image node_id 2 for calling the item obj's underlying member method code with example usage: obj.__repr__() and returns: unknown