class Matrix(object):
    def __init__(self, s):
        self.rows = [[int(n) for n in row.split()]
                     for row in s.split('\n')]

    @property
    def columns(self):
        return map(list, zip(*self.rows))

@@ -197,17 +197,29 @@
 urn 
-map(list,
+%5Blist(tup) for tup in
  zip
@@ -230,10 +230,10 @@
 lf.rows)
-)
+%5D
 %0A

Make matrix exercise compatible with Python3