code: def find(self, key):
      if not self.has_leaves():
          return None
      if key in self._leafs_:  # type: ignore
          return key
      return None
  
imports: from enum import IntEnum
  from typing import List
  import numpy
  from onnx.reference.op_run import OpRun
label_desc: Use image node_id 7 for calling the NgramPart obj's underlying member method code with example usage: obj.find(key) and returns: None, None, key