title: Navigate to lower level navigator from upper level component in react native
body: <p>Currently, I'm working on a react native mobile app. I have a stack navigator in the App.js file. (stack 1, stack 2, stack 3). In the stack 1 component, I have a tab navigator. (Tab 1, tab 2, tab 3). My goal is to navigate the tab 1 component using a function call (navigateToTab1(  ) ) in App.js.</p>
  <p>Any help on this task is really appreciated.</p>