Update README.MD

README.MD

@@ -2,12 +2,11 @@
 uln2003 for `MicroPython` has been in github, here's the [link](https://github.com/IDWizard/uln2003). But it's work for `microbit`, so I change a little to transplant for my NodeMCU's `ESP-32s`. Here's the example:
 ```python
 from stepper import Stepper
-from machine import Pin
 
-in1 = Pin(16,Pin.OUT)
-in2 = Pin(17,Pin.OUT)
-in3 = Pin(5,Pin.OUT)
-in4 = Pin(18,Pin.OUT)
+in1 = 16
+in2 = 17
+in3 = 5
+in4 = 18
 delay = 2
 mode = 1 # 0 for half step, 1 for full step
 
@@ -17,6 +16,9 @@ def main() -> None:
     s1.step(100,-1)
     s1.angle(180)
     s1.angle(360,-1)
+
+if __name__ == "__main__":
+    main()
 ```
 function `angle` is angle, and the PIN map:
 `IN1` link `PIN_16`