set-all-O(1)

Data structure which allow to set all values in it with complexity of O(1).

this is the description of the challenge:

build a data structure which contains the following operations

• set(index, x) -> will set the value at the index to x
• get(index) -> will get the value at index
• set_all(x) -> will set all the values in the datastructure to x
  

Note: all those operation should be done with the complexity of O(1)