code: def extern_call(self, context_handle, func, args_ptr, args_len):
      
      c = self._ffi.from_handle(context_handle)
      runnable = c.from_value(func[0])
      args = tuple(c.from_value(arg[0]) for arg in self._ffi.unpack(args_ptr, args_len))
      return self.call(c, runnable, args)
docs: Given a callable, call it.