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### Current Behavior
<!--- If describing a bug, tell us what happens instead of the expected behavior.
      Provide a screenshot when possible and full code sample -->
<!--- If suggesting a change/improvement, explain the difference from current behavior -->

### Expected Behavior
<!--- If you're describing a bug, tell us what should happen -->
<!--- If you're suggesting a change/improvement, tell us how it should work -->

### Your Environment
<!--- Include as many relevant details about the environment you experienced the bug in -->

| software         | version
| ---------------- | -------
| react-navigation |  
| react-native     |  
| node             | 
| npm or yarn      |