title: Kotlin- naming convention for boolean returning methods
body: <p>What is the naming convention for boolean returning methods?</p>
  
  <p>Using an 'is', 'has', 'should', 'can' in the front of method sound ok for some cases, but I'm not sure.
  Is there a better way to name such methods?
  for example: a function that checks card's validation. Should I call it <code>isValidCard</code> or <code>cardValidation</code> or another name?
  (I didn't find it here: <a href="https://kotlinlang.org/docs/reference/coding-conventions.html" rel="noreferrer">https://kotlinlang.org/docs/reference/coding-conventions.html</a>)</p>