title: Scala trait same method and argument with different return types
body: <p>I am on Scala 2.10.2 and trying to define a trait like </p>
  
  <pre><code>trait Foo {
    def bar(a:String): String
    def bar(a:String): Int
  }
  </code></pre>
  
  <p>Getting a compiler error <code>method a is defined twice</code>. What's the correct syntax?</p>