Update 02_07_challenge.py

Add comments to challenge file

exercise_files/02_07_challenge.py

@@ -2,21 +2,29 @@
 import time
 from termcolor import colored
 
+# This is the Canvas class. It defines some height and width, and a 
+# matrix of characters to keep track of where the TerminalScribes are moving
 class Canvas:
     def __init__(self, width, height):
         self._x = width
         self._y = height
+        # This is a grid that contains data about where the 
+        # TerminalScribes have visited
         self._canvas = [[' ' for y in range(self._y)] for x in range(self._x)]
 
+    # Returns True if the given point is outside the boundaries of the Canvas
     def hitsWall(self, point):
         return point[0] < 0 or point[0] >= self._x or point[1] < 0 or point[1] >= self._y
 
+    # Set the given position to the provided character on the canvas
     def setPos(self, pos, mark):
         self._canvas[pos[0]][pos[1]] = mark
 
+    # Clear the terminal (used to create animation)
     def clear(self):
         os.system('cls' if os.name == 'nt' else 'clear')
 
+    # Clear the terminal and then print each line in the canvas
     def print(self):
         self.clear()
         for y in range(self._y):
@@ -51,15 +59,24 @@ def left(self):
             self.draw(pos)
 
     def draw(self, pos):
+        # Set the old position to the "trail" symbol
         self.canvas.setPos(self.pos, self.trail)
+        # Update position
         self.pos = pos
+        # Set the new position to the "mark" symbol
         self.canvas.setPos(self.pos, colored(self.mark, 'red'))
+        # Print everything to the screen
         self.canvas.print()
+        # Sleep for a little bit to create the animation
         time.sleep(self.framerate)
 
+# Create a new Canvas instance that is 30 units wide by 30 units tall 
 canvas = Canvas(30, 30)
+
+# Create a new scribe and give it the Canvas object
 scribe = TerminalScribe(canvas)
 
+# Draw a small square
 scribe.right()
 scribe.right()
 scribe.right()