input: Write a python function to return a list of tuples containing index and value of each element in a list.
  assert index_and_value([2, 4, 6, 8, 10]) == [(0, 2), (1, 4), (2, 6), (3, 8), (4, 10)]
  assert index_and_value([1, 3, 5, 7]) == [(0, 1), (1, 3), (2, 5), (3, 7)]
  assert index_and_value([]) == []
output: def index_and_value(lst):
      return [(i, v) for i, v in enumerate(lst)]