Corrected typo.

line.py

@@ -107,7 +107,7 @@ def generate_line(root):
                 if op == '*':
                     left, right = node
 
-                    # Get the previous multiplcation element if the arity is #
+                    # Get the previous multiplcation element if the arity is
                     # greater than 2
                     if left.title() == '*':
                         left = left[1]