text: import { Component, Children } from 'react'
  import PropTypes from './prop-types'
  
  class Provider extends Component {
    getChildContext () {
      return {
        navigation: this.props.navigation
      }
    }
  
    render () {
      return Children.only(this.props.children)
    }
  }
  
  Provider.propTypes = {
    navigation: PropTypes.navigationShape.isRequired,
    children: PropTypes.element.isRequired
  }
  
  Provider.childContextTypes = {
    navigation: PropTypes.navigationShape.isRequired
  }
  
  export default Provider
  