title: Share code between google scripts
body: <p>I have a script that I use and update frequently for +3 spreadsheets, and I find it annoying to update each scripts separately every time. Would there be any ways to share (import/require) code from one place for each of those scripts?</p>
  
  <p>I cannot have all these spreadsheets in the same file since they concern different clients.</p>
  
  <p>My code contains functions as such:  </p>
  
  <pre><code>function onOpen() {
    var ui = SpreadsheetApp.getUi();
    ui.createMenu('Custom Export')
        .addItem('iOS', 'exportForIos')
        .addItem('Android', 'exportForAndroid')
        .addItem('JSON-iOS', 'exportJSONForIos')
        .addItem('JSON-Android', 'exportJSONForAndroid')
        .addToUi();
  }
  </code></pre>