Quick proof-of-concept for comparing python code using the abstract syntax tree as an alternative to pattern matching . It's a little more forgiving with whitespace, comments etc. First arg is the solution file, second is the attempt

gistfile1.py

import ast
import sys


def find_difference(a,b,lastpos=(0,0)):
	if isinstance(b,ast.expr) or isinstance(b,ast.stmt):
		lastpos = b.lineno,b.col_offset
	if type(a) != type(b): return lastpos
	if isinstance(a,ast.AST):
		for field in a._fields:
			r = find_difference(getattr(a,field),getattr(b,field),lastpos)
			if r: return r
	elif isinstance(a,list) or isinstance(a,tuple):
		for i,j in zip(a,b):
			r = find_difference(i,j,lastpos)
			if r: return r
	else:
		if a != b: return lastpos


def show_feedback(message,lines,ln,char):
	print 
	print message
	print 
	for j,line in enumerate(lines):
		print str(j+1).rjust(4)+": "+line,
		if j+1 != ln: continue
		print " "*5 + " "*char + "^"
		print " "*5 + " "*char + "'--- PROBLEM HERE"
		print 
	print


with open(sys.argv[1],"r") as f: ex_lines = f.readlines()
ex_tree = ast.parse("".join(ex_lines),sys.argv[1])

with open(sys.argv[2],"r") as f: ac_lines = f.readlines()
try:
	ac_tree = ast.parse("".join(ac_lines),sys.argv[2])
	
	diff = find_difference(ex_tree,ac_tree)
	if diff:
		show_feedback("Different from solution",ac_lines,diff[0],diff[1])
	else:
		print "Matches solution"
	
except SyntaxError as e:
	line,char = e.args[1][1:3]
	show_feedback("Syntax is incorrect",ac_lines,line,char)