class_docstr: A hash that generates group key and instance key for AllReduce.
docstr: Generate or retrieve the instance key based on the *original* variable op name.
docstr_tok: ["Generate","or","retrieve","the","instance","key","based","on","the","*","original","*","variable","op","name","."]
code: def get_instance_key(self, var_op_name):
      """Generate or retrieve the instance key based on the *original* variable op name."""
      key_id = var_op_name
      if key_id not in self._instance_key_dict:
          new_key = (
              int(hashlib.md5(var_op_name.encode()).hexdigest(), 16)
              % MAX_INT32
          )
          self._instance_key_dict[key_id] = new_key
      return self._instance_key_dict[key_id]
  
file_path: autodist/autodist/kernel/synchronization/collective_key.py
imports: import threading
  import hashlib
  from autodist.const import MAX_INT32
label_desc: Use image node_id 3 for calling the CollectiveKey obj's underlying member method code with example usage: obj.get_instance_key(var_op_name) and returns: self