def next(self):
    global p1
    if (self.btn.text == 'Start'):
        self.lbl_sec.start()
        self.btn.text = 'Next'
    else:
        p1 = get_num(self.pulse.text)
        if (p1 == False):
            self.pulse.text = ''
        else:
            self.manager.transition.direction = 'left'
            self.manager.current = '3'
def next(self):
    global p1
    if (self.btn.text == 'Start'):
        self.lbl_sec.start()
        self.btn.text = 'Next'
    else:
        p1 = get_num(self.pulse.text)
        if (p1 == False):
            self.pulse.text = 
        else:
            self.manager.transition.direction = 'left'
            self.manager.current = '3'