input: Write a function to determine the most efficient order of tasks from an array of given tasks. The function should take a list of tasks as input and return an ordered list of tasks representing the most efficient order for completing the tasks. If the input list of tasks is empty, the function should return an empty list.
  assert most_efficient_order([Task1, Task2, Task3, Task4, Task5]) == [Task4, Task1, Task2, Task3, Task5]
  assert most_efficient_order([Task3, Task5, Task1, Task2, Task4]) == [Task1, Task3, Task4, Task2, Task5]
  assert most_efficient_order([]) == []
output: def most_efficient_order(tasks):
      if not tasks:
          return []
      return sorted(tasks, key=lambda task: task.efficiency, reverse=True)