code: function assertHistoryType (history) {
    assertType("history", "object", history);
    assertType("history.listen", "function", history.listen);
    assertType("history.push", "function", history.push);
    assertType("history.replace", "function", history.replace);
    assertType("history.goBack", "function", history.goBack);
  }
docs: Throws an error if object shape is not that of a history object.
  
  @param  {History} history