Write a function that inputs a frequency, a maximum amplitude, a percentage of blend (e.g., 0.25 to represent 25%), and length in seconds. Create two sounds, one a square and one a triangle, using the same inputs. Add the sounds together, with the blend percentage of the square and 100—blend of the triangle. How does the sound change if you try 0.25, 0.5, and 0.75 as the blend percentages?