
  -spec spawn(Node, Module, Function, Args) -> pid()
                 when
                     Node :: node(),
                     Module :: module(),
                     Function :: atom(),
                     Args :: [term()].

  Returns the process identifier (pid) of a new process started by
  the application of Module:Function to Args on Node. If Node
  does not exist, a useless pid is returned. Otherwise works like 
  spawn/3.
