_onRefresh: function() {
   console.log("Refresh token " + this.state.token.idToken);
   lock.authenticationAPI()
     .refreshToken(this.state.token.refreshToken)
     .then(response => {
       let token = this.state.token;
       token.idToken = response.idToken;
       this.setState({token: token});
       console.log(response);
     })
     .catch(error => console.log(error));
 },
 _onUserInfo: function() {
   const token = this.state.token.accessToken;
   console.log("Fetching user info with token " + token);
   lock
     .authenticationAPI()
     .userInfo(token)
     .then(profile => {
       Alert.alert(
         `Hi ${profile.name}`,
         `Your email is ${profile.email}`,
         [
           {text: 'OK', onPress: () => {}},
         ]
       )
     })
     .catch(error => console.log(error));
 },