def is_disjoint(set1, set2, warn):
for elem in set2:<EOL><INDENT>if elem in set1:<EOL><INDENT>raise ValueError(warn)<EOL><DEDENT><DEDENT>return True<EOL>
Checks if elements of set2 are in set1.

:param set1: a set of values
:param set2: a set of values
:param warn: the error message that should be thrown
 when the sets are NOT disjoint
:return: returns true no elements of set2 are in set1