title: TS1183: implementation cannot be declared in ambient context in Typescript
body: <p>Im trying to make a global namespace/function
  my code looks like this : abc.ts</p>
  
  <pre><code>declare namespace abc {
     export function abc (): xyz {
          console.log('Hello');
          return xyz(200);
      }
  }
  export = abc
  </code></pre>
  
  <p>What am I doing wrong? How do I fix it ? </p>