title: How to implement a button on the left side of the header in react-navigation
body: <p>I have a main Stack navigator(X) and inside that I have screen which takes me to another stack navigator(A). But when I go stack(A) it's not showing me the button to go back to stack(X). I do understand that using multiple stack navigators like these is not the best practice, but I want to implement a Tab navigator inside of stack(A) and each of the tabs would contain a stack navigator.</p>
  
  <p>I have tried implementing a button as described <a href="https://reactnavigation.org/docs/header-buttons/" rel="nofollow noreferrer">on the react-navigation docs</a>, but it doesn't describe how to implement it on the left side of the header.</p>
  
  <p>How do I get around this?</p>