Remove trailing whitespace.

functions/classes.py

@@ -435,7 +435,7 @@ def print_assembly_tree(root, levels=None):
 
     Args:
         root (LegoAssembly): The root of the assembly tree to print.
-        levels (List[bool]): Internally used by recursion to know where 
+        levels (List[bool]): Internally used by recursion to know where
             to print vertical connection. Defaults to an empty list.
     """
     if not isinstance(root, LegoAssembly):