Comprehensions: squares of evens

A list comprehension builds a new list in one expressive line. It pairs a transform with an optional filter:

nums = [1, 2, 3, 4]
[n + 10 for n in nums]        # [11, 12, 13, 14]  — transform every item
[n for n in nums if n > 2]    # [3, 4]             — keep only some items

You can do both at once: transform the items that pass the filter.

Your task

Write even_squares(nums) that returns a list of the squares of the even numbers in nums, keeping the original order.

even_squares([1, 2, 3, 4])   # [4, 16]
even_squares([2, 4, 6])       # [4, 16, 36]
even_squares([])              # []

Hint: a single comprehension can filter and transform at once — keep the numbers that pass your even-test, and square each one that survives.