code: def reveal_undocumented(symbol_name, target_module=None):
      """Reveals a symbol that was previously removed by `remove_undocumented`.
  
      This should be used by tensorflow internal tests only. It explicitly
      defeats the encapsulation afforded by `remove_undocumented`.
  
      It throws an exception when the symbol was not hidden in the first place.
  
      Args:
        symbol_name: a string representing the full absolute path of the symbol.
        target_module: if specified, the module in which to restore the symbol.
      """
      if symbol_name not in _HIDDEN_ATTRIBUTES:
          raise LookupError(
              "Symbol %s is not a hidden symbol" % symbol_name
          )
      symbol_basename = symbol_name.split(".")[-1]
      (original_module, attr_value) = _HIDDEN_ATTRIBUTES[symbol_name]
      if not target_module:
          target_module = original_module
      setattr(target_module, symbol_basename, attr_value)
  
imports: import re
  import sys
  from tensorflow.python.util import tf_inspect
label_desc: Use image node_id 2 for calling a global function with example usage: reveal_undocumented(symbol_name, target_module) without return types