input: Write a function to calculate the sum of all elements in a list using lambda function and reduce.
  assert sum_of_elements([1, 2, 3, 4, 5]) == 15
  assert sum_of_elements([10, 20, 30, 40, 50]) == 150
  assert sum_of_elements([5, -5, 10, -10]) == 0
output: from functools import reduce
  
  def sum_of_elements(lst):
      return reduce(lambda x, y: x + y, lst)