Error: 'PWM' Object Has No Attribute 'duty' in Motor Control Code Using MicroPython

from machine import Pin, PWM
import time

motor1_pwm = PWM(Pin(14), freq=1000)

motor1_in1 = Pin(12, Pin.OUT)          

motor1_in2 = Pin(13, Pin.OUT)          

def forward(speed):
    motor1_in1.on()
    motor1_in2.off()
    motor1_pwm.duty(int(speed * 1023))

def reverse(speed):
    motor1_in1.off()
    motor1_in2.on()
    motor1_pwm.duty(int(speed * 1023))

def stop():
    motor1_in1.off()
    motor1_in2.off()
    motor1_pwm.duty(0)

while True:
    forward(0.7)
    time.sleep(2)
    reverse(0.5)
    time.sleep(2)
    stop()
    time.sleep(2)