function divisibleBy5(array) {
  function isDivisible(num) {
    return num % 5 === 0;
  }
  return array.find(isDivisible);
}


/* From here down, you are not expected to
   understand.... for now :)


   Nothing to see here!

*/


// tests

function testFunctionWorks(fn, input, expected) {

  if (fn(input) === expected) {
    console.log('SUCCESS: `' + fn.name + '` works on `[' + input + ']`');
    return true;
  }
  else {
    console.error(
      'FAILURE: `' + fn.name + '([' + input + '])` should be ' + expected +
      ' but was ' + fn(input)
    );
    return false;
  }
}

function runTests() {

  var input1 = [13, 22, 4, 47, 15, 35, 82];
  var result1 = 15;
  var input2 = [25, 20, 15, 10, 5];
  var result2 = 25;

  var testResults = [
    testFunctionWorks(divisibleBy5, input1, result1),
    testFunctionWorks(divisibleBy5, input2, result2),
  ];



  var numPassing = testResults.filter(function(result){ return result; }).length;
  console.log(numPassing + ' out of ' + testResults.length + ' tests passing.');
}

runTests();