Monday Mutant 30: Double Entry

Draw a single loop that connects the grid cells. The loop may only travel horizontally or vertically, and never diagonally (so all turns are of 90 degrees). The loop may only turn at the centers of grid cells, and may not cross itself or branch off. Every grid cell must be used, and the loop must enter and exit every region of the grid exactly twice. (The regions are colored as an aesthetic only.)