public function testValidEmailAddress()
 {
     $validEmails = array('*****@*****.**', '*****@*****.**');
     $invalidEmails = array('foo.bar@', '@example.com', 'foo@');
     foreach ($validEmails as $email) {
         $this->assertTrue(Email::is_valid_address($email), 'is_valid_address() returns true for a valid email address');
     }
     foreach ($invalidEmails as $email) {
         $this->assertFalse(Email::is_valid_address($email), 'is_valid_address() returns false for an invalid email address');
     }
 }