def whos_allowed(self):
        """Returns set containing any entries from principal and condition section.
        
        Example:
        
        statement = Statement(dict(
            Effect='Allow',
            Principal='arn:aws:iam::*:role/Hello',
            Action=['ec2:*'],
            Resource='*',
            Condition={
                'StringLike': {
                    'AWS:SourceOwner': '012345678910'
                }}))

        statement.whos_allowed()
        > set([
        >    PrincipalTuple(category='principal', value='arn:aws:iam::*:role/Hello'),
        >    ConditionTuple(category='account', value='012345678910')])
        """
        who = set()
        for principal in self.principals:
            principal = PrincipalTuple(category='principal', value=principal)
            who.add(principal)
        who = who.union(self.condition_entries)
        return who