title: Better way to express "if false return false" construct
body: <p>In many cases you have code like this (C-style pseudo code used):</p>
  
  <pre><code>bool checkCondition();
  
  bool doSomething(){
     if (checkCondition() == false)
        return false;
  
     // do something
     return true;
  }
  </code></pre>
  
  <p>I keep reusing this patter and every time wonder, if there is better way to express it?</p>
  
  <p>Sometimes, the condition check can be left for the caller or asserted, but often condition check must be done inside the function.</p>
  
  <p>You can get fancy and use exceptions, but result is almost the same code.</p>