title: Counter as variable in for-in-loops
body: <p>When normally using a for-in-loop, the counter (in this case <code>number</code>) is a constant in each iteration:</p>
  
  <pre><code>for number in 1...10 {
      // do something
  }
  </code></pre>
  
  <p>This means I cannot change <code>number</code> in the loop:</p>
  
  <pre><code>for number in 1...10 {
      if number == 5 {
          ++number
      }
  }
  
  // doesn't compile, since the prefix operator '++' can't be performed on the constant 'number'
  </code></pre>
  
  <p>Is there a way to declare <code>number</code> as a variable, without declaring it before the loop, or using a normal for-loop (with initialization, condition and increment)?</p>