Fix #140 (#164)
Fix #140 (#164)

Changed error message when no __len__
IronLanguages/ironpython2,slozier/ironpython2,slozier/ironpython2,slozier/ironpython2,slozier/ironpython2,IronLanguages/ironpython2,IronLanguages/ironpython2,slozier/ironpython2,IronLanguages/ironpython2,slozier/ironpython2,IronLanguages/ironpython2,IronLanguages/ironpython2,slozier/ironpython2,IronLanguages/ironpython2