input: Write a python function that calculates the total of all even natural numbers between l and r inclusive.
  assert sum_Even(2, 5) == 6
  assert sum_Even(3, 8) == 18
  assert sum_Even(4, 6) == 10
output: def sum_Even(l, r):
      return sum(i for i in range(l, r + 1) if i % 2 == 0)