input: Write a function to perform a linear search in an array. The function should take an array and a value to search for, and return the index of the value if it is found, or -1 if it is not found.
  
  def linearSearch(arr, value):
    for i in range(len(arr)):
      if arr[i] == value:
        return i  # value found, return index
    return -1  # value not found
  
  assert linearSearch([5, 3, 7, 2], 7) == 2
  assert linearSearch([5, 3, 7, 2], 9) == -1
  assert linearSearch([], 7) == -1
  assert linearSearch([5, 3, 7, 2], 2) == 3
  assert linearSearch([5, 3, 7, 2], 3) == 1
output: def linearSearch(arr, value):
    for i in range(len(arr)):
      if arr[i] == value:
        return i
    return -1