Added documentation for open
Added documentation for open

lucidfrontier45/ScalaFunctional,ChuyuHsu/ScalaFunctional,lucidfrontier45/ScalaFunctional,ChuyuHsu/ScalaFunctional,EntilZha/ScalaFunctional,EntilZha/ScalaFunctional,EntilZha/PyFunctional,EntilZha/PyFunctional