Squishing a List

Write a function that squishes a list from the left or the right.

Examples

squish([1, 2, 3, 4, 5], "left")
➞ [[1, 2, 3, 4, 5], [3, 3, 4, 5], [6, 4, 5], [10, 5], [15]]

squish([1, 2, 3, 4, 5], "right")
➞ [[1, 2, 3, 4, 5], [1, 2, 3, 9], [1, 2, 12], [1, 14], [15]]

squish([1, 0, 2, -3], "left")
➞ [[1, 0, 2, -3], [1, 2, -3], [3, -3], [0]]

squish([1, 0, 2, -3], "right")
➞ [[1, 0, 2, -3], [1, 0, -1], [1, -1], [0]]

Notes

• Squishing from the left is to successively sum the first two elements of a list (shortening the list in the process).
• Squishing from the right is to successively sum the last two elements of a list.
• Include the original list as the first element in either squish.
• Return an empty list if the input is an empty list.