docstr: get all keys of the InputFeatures
  
  Args:
      keep_none (:obj:`bool`, optional): whether to keep the predefined keys whose value is none. Defaults to False.
  
  Returns:
      :obj:`List[str]`: keys of the InputFeatures
docstr_tok: ["get","all","keys","of","the","InputFeatures","Args",":","keep_none","(",":","obj",":","`","bool","`",",","optional",")",":","whether","to","keep","the","predefined","keys","whose","value","is","none",".","Defaults","to","False",".","Returns",":",":","obj",":","`","List","[","str","]","`",":","keys","of","the","InputFeatures"]
code: def keys(self, keep_none=False) -> List[str]:
      """get all keys of the InputFeatures
  
      Args:
          keep_none (:obj:`bool`, optional): whether to keep the predefined keys whose value is none. Defaults to False.
  
      Returns:
          :obj:`List[str]`: keys of the InputFeatures
      """
      if keep_none:
          return self.all_keys
      else:
          return [
              key
              for key in self.all_keys
              if getattr(self, key) is not None
          ]
  
imports: import copy
  import json
  import pickle
  from typing import *
  import paddle
label_desc: Use image node_id 11 for calling the InputFeatures obj's underlying member method code with example usage: obj.keys(keep_none) and returns: self, unknown