title: Do I need to declare a global variable inside every external typescript module?
body: <p>I've been using one global variable called system which is defined in index.ts.
  When I was using internal modules that went fine, probably because I started compiling in index.ts with --out. </p>
  
  <p>Now I'm switching to external modules the compiler throws errors for the global variable 'system'.
  I kept a single  in each file with some .d.ts files for external libs, and I tried adding</p>
  
  <pre><code>declare var system:System
  </code></pre>
  
  <p>in that shared reference file, but that didnt work.</p>
  
  <p>What does work is adding the declare statement to each file that uses the global variable.
  So my question is if this is the way I should do it (declaring in every file), or if there's something I'm missing.</p>
  
  <p>Tnx!</p>