old_contents: import React, { Component } from 'react';
  import { StyleSheet, Text, View } from 'react-native';
  
  import { Page, Button } from 'HowMany/src/components';
  import appStyle from 'HowMany/src/appStyle';
  
  const styles = StyleSheet.create({
    container: {
      flex: 1,
      justifyContent: 'center',
      alignItems: 'center',
    },
    welcome: {
      fontSize: appStyle.font.size.huge,
      textAlign: 'center',
      margin: appStyle.grid.x1,
    },
    instructions: {
      textAlign: 'center',
      color: appStyle.colors.darkGray,
      marginBottom: appStyle.grid.x1,
    },
  });
  
  type PropsType = {
    navigation: any,
  };
  
  class Home extends Component {
    static navigationOptions = {
      title: 'Home',
    };
    props: PropsType;
  
    _goToInfos = () => {
      this.props.navigation.navigate('infos');
    }
  
    render() {
      return (
        <Page>
          <View style={styles.container}>
            <Text style={styles.welcome}>
              Welcome to React Native!
            </Text>
            <Text style={styles.instructions}>
              This is the Home page
            </Text>
            <Text style={styles.instructions}>
              Double tap R on your keyboard to reload,{'\n'}
              Shake or press menu button for dev menu
            </Text>
            <Button onPress={this._goToInfos}>Go to the Infos page</Button>
          </View>
        </Page>
      );
    }
  }
  
  export default Home;
  
new_contents: import React, { PureComponent } from 'react';
  import { StyleSheet, Text, View } from 'react-native';
  
  import { Page, Button } from 'HowMany/src/components';
  import appStyle from 'HowMany/src/appStyle';
  
  const styles = StyleSheet.create({
    container: {
      flex: 1,
      justifyContent: 'center',
      alignItems: 'center',
    },
    welcome: {
      fontSize: appStyle.font.size.huge,
      textAlign: 'center',
      margin: appStyle.grid.x1,
    },
    instructions: {
      textAlign: 'center',
      color: appStyle.colors.darkGray,
      marginBottom: appStyle.grid.x1,
    },
  });
  
  type PropsType = {
    navigation: any,
  };
  
  class Home extends PureComponent {
    static navigationOptions = {
      title: 'Home',
    };
    props: PropsType;
  
    _goToInfos = () => {
      this.props.navigation.navigate('infos');
    }
  
    render() {
      return (
        <Page>
          <View style={styles.container}>
            <Text style={styles.welcome}>
              Welcome to React Native!
            </Text>
            <Text style={styles.instructions}>
              This is the Home page
            </Text>
            <Text style={styles.instructions}>
              Double tap R on your keyboard to reload,{'\n'}
              Shake or press menu button for dev menu
            </Text>
            <Button onPress={this._goToInfos}>Go to the Infos page</Button>
          </View>
        </Page>
      );
    }
  }
  
  export default Home;
  
subject: Use PureComponent