parameters: (self, pid, callback, *args)
docstring: Register a new child handler.
  
          Arrange for callback(pid, returncode, *args) to be called when
          process 'pid' terminates. Specifying another callback for the same
          process replaces the previous handler.
  
          Note: callback() must be thread-safe.
docstring_summary: Register a new child handler.
docstring_tokens: Register a new child handler .
function: def add_child_handler(self, pid, callback, *args):
          """Register a new child handler.
  
          Arrange for callback(pid, returncode, *args) to be called when
          process 'pid' terminates. Specifying another callback for the same
          process replaces the previous handler.
  
          Note: callback() must be thread-safe.
          """
          raise NotImplementedError()
function_tokens: def add_child_handler ( self , pid , callback , * args ) : raise NotImplementedError ( )