Suppose you have a list of rectangles, rect_list. Each rectangle is represented by a tuple (x, y, w, h) where x and y are the coordinates of the upper left corner of the rectangle, and w and h are the width and height of the rectangle. Write a function that returns a list containing every pair of overlapping rectangles from rect_list. Each pair should be represented as a tuple of indices from rect_list (e. g., [(0,1), (2,4)] indicates that rectangles 0 and 1 overlap, and rectangles 2 and 4 overlap).