function removeDuplicates(arr) {
  var clean = []
  var cleanLen = 0
  var arrLen = arr.length

  for (var i = 0; i < arrLen; i++) {
    var el = arr[i]
    var duplicate = false

    for (var j = 0; j < cleanLen; j++) {
      if (el !== clean[j]) continue
      duplicate = true
      break
    }

    if (duplicate) continue
    clean[cleanLen++] = el
  }

  return clean
}