Robot RC car mode 1st draft

import RPi.GPIO as GPIO
import time
from time import sleep

# global vars

pwmpinL = 18
pwmpinR = 13
directionL = 22
directionR = 23
pwmfreq=1000 # set PWM frequency to 10Khz, compatible with slow slew mode on the motor controller
dc = 25 # percent duty cycle to test with

GPIO.setmode(GPIO.BCM) # set pin selection mode
GPIO.setup(pwmpinL, GPIO.OUT) #set left motor's pin to output mode
GPIO.setup(pwmpinR, GPIO.OUT) #set right motor's pin to output mode
GPIO.setup(directionL, GPIO.OUT) #set right motor's pin to output mode
GPIO.setup(directionR, GPIO.OUT) #set right motor's pin to output mode

pwmL = GPIO.PWM(pwmpinL, pwmfreq)
pwmR = GPIO.PWM(pwmpinR, pwmfreq)
#dirL = GPIO.OUT(directionL, 1)
#dirR = GPIO.OUT(directionR, 1)

#GPIO.output(pwmpinL, GPIO.LOW)

# Some simple predefined motor control functions

def stopmotors():
    global dc
    pwmL.stop()
    pwmR.stop()
    return

def turnright():
    global dc
    pwmR.stop()
    pwmL.start(dc)
    return

def turnleft():
    global dc
    pwmL.stop()
    pwmR.start(dc)
    return

def gostraight():
    global dc
    pwmL.start(dc) #start running left motor at test duty cycle
    pwmR.start(dc) #start running left motor at test duty cycle
    return

def changespeed(newspeed):
    global dc
    dc=newspeed*25
    return

# Code to get keypresses

class _Getch:
    """Gets a single character from standard input.  Does not echo to the
screen."""
    def __init__(self):
        try:
            self.impl = _GetchWindows()
        except ImportError:
            self.impl = _GetchUnix()

    def __call__(self): return self.impl()

class _GetchUnix:
    def __init__(self):
        import tty, sys

    def __call__(self):
        import sys, tty, termios
        fd = sys.stdin.fileno()
        old_settings = termios.tcgetattr(fd)
        try:
            tty.setraw(sys.stdin.fileno())
            ch = sys.stdin.read(1)
        finally:
            termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
        return ch


class _GetchWindows:
    def __init__(self):
        import msvcrt

    def __call__(self):
        import msvcrt
        return msvcrt.getch()


print("Use W/A/S/D to move, numbers 1~4 to adjust movement speed. Press C to exit")

# Keypress polling loop
while True:
    getch = _Getch()
    if (getch=="w"):
        gostraight()
    if (getch=="a"):
        turnleft()
    if (getch=="d"):
        turnright()
    if (getch=="s"):
        stopmotors()
    if (getch=="1"):
        changespeed(1)
    if (getch=="2"):
        changespeed(2)
    if (getch=="3"):
        changespeed(3)
    if (getch=="4"):
        changespeed(4)
    if (getch=="c"):
        stopmotors()
        break
    sleep(0.05)


GPIO.cleanup()