Challenge

Past

One concept, three rungs. Reaching rung 1 is the goal, so climb as far as you can.

Building A New List

loops + making lists

Rung 1Daily goal5 points

Double everything

Write a function called double_all

Return a new list where every number is twice as big. The old list is not changed, and an empty list gives an empty list.

Examples

Input	Output
[1, 2, 3]	[2, 4, 6]
[]	[]
[0]	[0]
[-2]	[-4]

There are extra hidden tests, so make it work in general, not just for these.

Rung 2Bonus7 points

Keep the positive ones

Write a function called keep_positive

Return a new list holding only the numbers bigger than 0, in the same order. Zero is not positive, so it does not go in.

Examples

Input	Output
[1, -2, 3]	[1, 3]
[]	[]
[-1]	[]
[0, 2]	[2]

There are extra hidden tests, so make it work in general, not just for these.

Rung 3Bonus10 points

Bigger than the one before

Write a function called bigger_than_before

Return a new list of the numbers that are bigger than the number just in front of them. The very first number is never included, and two equal numbers do not count. So [1, 3, 2, 5] gives [3, 5].

Examples

Input	Output
[1, 3, 2, 5]	[3, 5]
[]	[]
[5]	[]
[3, 3]	[]

There are extra hidden tests, so make it work in general, not just for these.

Finish Rung 1 and today counts. Rungs 2 and 3 are there if you want to push further.