code: function consumeKeywordOrFunction(stream) {
  	const kw = consumeKeyword(stream);
  	if (kw) {
  		const args = consumeArgumentList(stream);
  		return args ? new FunctionCall(kw.toString(), args) : kw;
  	}
  }
docs: Consumes either function call like `foo()` or keyword like `foo`
  @param  {StreamReader} stream
  @return {Keyword|FunctionCall}