input: Write a function to determine the most efficient order of tasks from an array of given tasks. If the tasks list is empty, return an empty list. The function should return a list of tasks such that tasks with shorter execution times are placed earlier in the list.
  
  assert most_efficient_order([Task1, Task2, Task3, Task4, Task5])==[Task4, Task1, Task3, Task5, Task2]
  assert most_efficient_order([Task1, Task2, Task3])==[Task2, Task1, Task3]
  assert most_efficient_order([Task1])==[Task1]
  assert most_efficient_order([])==[]
output: def most_efficient_order(tasks):
      return sorted(tasks, key=lambda task: task.execution_time)