def merge_sorted(left: list[int], right: list[int]) -> list[int]:
    """Merge two sorted lists into one sorted list."""
    merged = []
    i = 0
    j = 0

    # BUG: should continue while BOTH lists still have elements,
    # and then append remainders.
    while i < len(left) and j < len(right):
        if left[i] < right[j]:
            merged.append(left[i])
            i += 1
        else:
            merged.append(right[j])
            j += 1

    return merged