# 
# 7B
# Gradation of size and width of black keys,
# from heavy and dark to tiny and light
import math
g.norefresh()

def movingup(x1, x2, k, j):
	for i in range (k, (k+j)):
      	g.pen(100)
        g.line(x1, i, x2, i)
	g.refresh()
	g.pen(0)
	g.line(x1, i, x2, i)

def movingdown(x1, x2, k, j, space):
        for i in range (0, j):
		g.pen(100)
		g.line(x1, (space+k-i), x2, (space+k-i))
		g.refresh()
		g.pen(0)
		g.line(x1, (space+k-i), x2, (space+k-i))

def keys (x, y, width, space):
 	 for j in range (0, 10):
	        if(j<5):
	 	       	movingup(x, y, 50, (50-(10*j)))
			for i in range ((10*j), ((10*j)+width)):
				g.pen(100)
			        g.line(x, (100-i), y, (100-i))
			        g.refresh()  
			        movingdown(x, y, 50, (50-(10*j)), space)
			        for i in range (((10*j)+space), (((10*j)+width))+space):
			        g.pen(100)
			        g.line(x, i, y, i)
				g.refresh()


def fish(x, y):
	g.pen(100)
	g.line(x, 50, y, 50)
	g.pause(4)
	g.refresh()
	g.pen(0)
	g.line(x, 50, y, 50)


g.paper(0)
fish(2, 5)
fish(10, 20)
fish(23, 37)
fish(40, 62)
g.line(65, 100, 100, 50)
g.refresh()
keys(65, 100, 9, 1)
g.line(65, 51, 100, 51)

fish(2, 5)
fish(10, 20)
fish(23, 37)
fish(40, 62)
keys(40, 62, 7, 3) 

fish(2, 5)
fish(10, 20)
fish(23, 37)
keys(23, 37, 5, 5) 
g.line(23, 0, 37, 0)

fish(2, 5)
fish(10, 20)
keys(10, 20, 2, 8)
g.line(10, 0, 20, 0)

fish(4, 5)
keys(4, 5, 1, 9)
g.line(4, 1, 5, 1)