from pynput import keyboard, mouse
import random
import time
import os


trials = int(input('Number of trials?'))

random.seed()

cls = lambda: os.system('cls')

def on_release(key):
    return key != keyboard.Key.esc

def on_click(x, y, button, pressed):
    return not pressed

tr1 = lambda x : True
tr2 = lambda x,y : True
tr4 = lambda x,y,z,w : True

lst_mouse_press = []
lst_key_rel = []

for i in range(trials):
    rand_time = random.randrange(2000,6000)/1000.
    cls()
    print('Press RMB')
    print('Trial: ' + str(i))
    time.sleep(rand_time)
    print('NOW!')
    t1 = time.perf_counter()
    with mouse.Listener(on_move=tr2, on_click=on_click, on_scroll=tr4) as listener:
        listener.join()
    t2 = time.perf_counter()
    lst_mouse_press.append(t2-t1)

for i in range(trials):
    rand_time = random.randrange(2000,6000)/1000.
    cls()
    print('Release ESC')
    print('Trial: ' + str(i))
    time.sleep(rand_time)
    print('NOW!')
    t1 = time.perf_counter()
    with keyboard.Listener(on_press=tr1, on_release=on_release) as listener:
        listener.join()
    t2 = time.perf_counter()
    lst_key_rel.append(t2-t1)


avg = lambda x : round(1000.*sum(x)/len(x))

mouse_press_time = avg(lst_mouse_press)
key_rel_time = avg(lst_key_rel)

print('Mouse press: ' + str(mouse_press_time) + 'ms')
print('Key release: ' + str(key_rel_time) + 'ms')

t.py:34: Warning: 'with' will become a reserved keyword in Python 2.6
  Line 34
    with mouse.Listener(on_move=tr2, on_click=on_click, on_scroll=tr4) as listener:
             ^
SyntaxError: invalid syntax