input: Write a python function to perform a linear search in a list.
  assert linearSearch([2, 3, 4, 6, 1], 4) == 2
  assert linearSearch([2, 3, 4, 6, 1], 5) == -1
  assert linearSearch([10, 20, 30, 40, 50], 30) == 2
  assert linearSearch([1, 2, 3, 4, 5], 1) == 0
output: def linearSearch(lst, target):
      for i in range(len(lst)):
          if lst[i] == target:
              return i
      return -1