I've noticed recently that a lot of people are declaring functions in their functional components using the function keyword instead of using arrow functions. I'm wondering if there is a performance reason for this, or is a style thing, or something else? 
For example say I have a component ShowNote with a form and a function to validate it, I could declare it like this:
const ShowNote = () => {
  function validateForm() {
    return content.length > 0;
  }
  ...
or
const ShowNote = () => {
  const validateForm = () => {
    return content.length > 0;
  }
...
