Issue Description:

Steps :

1. Create a subarray

2. Find the index of an item from the subarray

Problem :

• It is returning the index from the original array.

  var originalArray = [1, 2, 3, 4, 5, 6, 7]
  print("original array : \(originalArray)")
  let indexA = originalArray.index(of: 5)!
  print("index of #​5 : \(indexA)")
  let subArray = originalArray[3 ..< originalArray.count]
  print("subarray : \(subArray)")
  let indexB = subArray.index(of: 5)!
  print("index of #&#8203;5 : \(indexB)")

  // output
  original array : [1, 2, 3, 4, 5, 6, 7]
  index of #​5 : 4
  subarray : [4, 5, 6, 7]
  index of #​5 : 4

• The last index should be 1 not 4.