def does_not_contain_duplicates(self):
try:<EOL><INDENT>if len(self.val) == len(set(self.val)):<EOL><INDENT>return self<EOL><DEDENT><DEDENT>except TypeError:<EOL><INDENT>raise TypeError('<STR_LIT>')<EOL><DEDENT>self._err('<STR_LIT>' % self.val)<EOL>
Asserts that val is iterable and does not contain any duplicate items.