code: def keys(node, field_name="___pyct_anno"):
      if not hasattr(node, field_name):
          return frozenset()
      return frozenset(getattr(node, field_name).keys())
  
file_path: tensorflow-upstream/tensorflow/python/autograph/pyct/anno.py
imports: import enum
  import gast
label_desc: Use image node_id 1 for calling a global function with example usage: keys(node, field_name) and returns: frozenset, frozenset