docs: add commentaries and code description

examples/back_switch.py

@@ -1,32 +1,59 @@
+"""
+This example demonstrates how to move the motor after hitting a switch.
+It also shows the use of Crappy Blocks outside a Crappy loop.
+
+In this example, a Tkinter slider controlled by the user sends command to the
+Actuator Block. The slider sends speed command to drive the motor here.
+The user can only drive the motor in the opposite direction of the switch that
+has been hit.
+
+The test ends when the slider window is closed.
+"""
+
 import crappy
 import tkinter as tk
 
 if __name__ == '__main__':
 
   open_switch = 0
 
+  # This Actuator drives a Phidget4AStepper in speed.
   mot = crappy.actuator.Phidget4AStepper(
-    steps_per_mm=2500,
-    current_limit=3,
-    max_acceleration=20,
-    remote=True,
-    switch_ports=(5, 6))
+    steps_per_mm=2500,  # Number of steps necessary to move by 1 mm.
+    current_limit=3,  # Maximum current the driver is allowed to deliver
+    # to the motor, in A.
+    max_acceleration=20,  # Maximum acceleration the motor is allowed to
+    # reach in mm/s².
+    remote=True,  # True if connected to a wireless VINT Hub, False if
+    # connected to a USB VINT Hub.
+    switch_ports=(5, 6)  # Port numbers of the VINT Hub where the
+    # switches are connected.
+  )
 
+  # Remove the automatic check of the state of the switches
   mot._check_switch = False
+
+  # Open the Actuator
   mot.open()
+
+  # Find the switch that has been hit
   for switch in mot._switches:
     if switch.getState() is False:
       open_switch = switch.getHubPort()
 
 
-  def gen_speed(value):
+  def gen_speed(value) -> None:
+    """Callback sending the speed command to the driver when the user update
+    the slider value. """
+
     mot.set_speed(float(value))
 
 
-  # Creates the graphical interface
+  # Create the graphical interface
   root = tk.Tk()
   root.title("Motor speed")
 
+  # Create the slider associate to the switch hit
   if open_switch == 5:
     # Create the slider
     slider = tk.Scale(root,