Flatten A List Of Lists

Write a function flatten(lol) that takes a list of lists and returns a single flat list containing every element of every inner list, keeping the original order.

Example

flatten([[1, 2], [3]])  ->  [1, 2, 3]

Your task

Implement this function:

def flatten(lol: list) -> list:

Write the function only — the arguments are read for you and the return value is printed automatically.

Arguments arrive as one Python literal per line, in this order: lol.

Example

Input

[[1, 2], [3]]

Output

[1, 2, 3]