old_contents: import React, { Component, PropTypes } from 'react';
  import { connect, observer } from 'utils';
  
  export default class Landing extends Component {
    static propTypes = {
      language: PropTypes.string,
      setLanguage: PropTypes.func,
      helloMessage: PropTypes.string,
    }
  
    render() {
      const { helloMessage, setLanguage, language } = this.props;
  
      return (
        <div>
          <p>{helloMessage}</p>
          <button
            onClick={() => setLanguage(language === 'en' ? 'pl' : 'en')}
          >Toggle language</button>
        </div>
      );
    }
  }
  
new_contents: import React, { Component, PropTypes } from 'react';
  import { connect, observer } from 'utils';
  
  @observer
  @connect(({ userStore, uiStore }) => ({
    language: uiStore.language,
    setLanguage: uiStore.setLanguage,
    helloMessage: userStore.helloMessage,
  }))
  export default class Landing extends Component {
    static propTypes = {
      language: PropTypes.string,
      setLanguage: PropTypes.func,
      helloMessage: PropTypes.string,
    }
  
    render() {
      const { helloMessage, setLanguage, language } = this.props;
  
      return (
        <div>
          <p>{helloMessage}</p>
          <button
            onClick={() => setLanguage(language === 'en' ? 'pl' : 'en')}
          >Toggle language</button>
        </div>
      );
    }
  }
  
subject: Add store connect