Synthesizer

import play
import pygame

play.set_backdrop('light blue')
introduce1 = play.new_text(words='Piano for fun!', x=0, y=200)
introduce2 = play.new_text(words='Create your melody by pressing the keys', x=0, y=150)

p = play.new_box(color='green', x=-100, y=-170, width=160, height=50)
p_text = play.new_text(words='play melody', x=-100, y=-170, font_size=20)

c = play.new_box(color='yellow',  x=100, y=-170, width=160, height=50)
c_text = play.new_text(words='clear melody', x=100, y=-170, font_size=20)

b_p = play.new_circle(x=-180, y=-100, radius=10)
txt_p = play.new_text(words='piano', x=-145, y=-100, font_size=20)

b_g = play.new_circle(color='blue', x=-80, y=-100, radius=10)
txt_g = play.new_text(words='guitar', x=-45, y=-100, font_size=20)

b_v = play.new_circle(color='blue', x=20, y=-100, radius=10)
txt_v = play.new_text(words='violin', x=55, y=-100, font_size=20)

b_f = play.new_circle(color='blue', x=120, y=-100, radius=10)
txt_f = play.new_text(words='flute', x=155, y=-100, font_size=20)

instrument = 0
instrument_buttons = [b_p, b_g, b_v, b_f]

@play.repeat_forever
def switch():
    for i in instrument_buttons:
        if i.is_clicked:
            global instrument
            instrument = instrument_buttons.index(i)
            for j in instrument_buttons:
                j.color = "blue"
            i.color = "black"

keys = []
sounds = [[], [], [], []]
colors = ["red", "orange", "yellow", "green", "dark green", "blue", "indigo", "purple"]
buttons = ["a", "s", "d", "f", "g", "h", "j", "k"]

for i in range(8):
    key_x = -180 + i * 50
    key = play.new_box(color=colors[i], x=key_x, width=40, height=100)
    keys.append(key)
    p_sound = pygame.mixer.Sound("pia" + str(i+1)+'.ogg')
    g_sound = pygame.mixer.Sound("git" + str(i+1)+'.ogg')
    v_sound = pygame.mixer.Sound("vio" + str(i+1)+'.ogg')
    f_sound = pygame.mixer.Sound("fl" + str(i+1)+'.ogg')
    sounds[0].append(p_sound)
    sounds[1].append(g_sound)
    sounds[2].append(v_sound)
    sounds[3].append(f_sound)

@play.when_program_starts
def start():
    pygame.mixer_music.load('hi-1.mp3')
    pygame.mixer_music.play()

melody = []

@play.repeat_forever
async def play_instrument():
    for i in range(len(keys)):
        if keys[i].is_clicked or play.key_is_pressed(buttons[i]):
            keys[i].color = 'light grey'
            sounds[instrument][i].play()
            await play.timer(seconds=0.1)
            keys[i].color = colors[i] #alternately, "white"
            melody.append(i)

@p.when_clicked
async def play_m():
    for i in range(len(melody)):
        await play.timer(seconds=0.5)
        sounds[instrument][melody[i]].play()

@c.when_clicked
def clear():
    melody.clear()

play.start_program()