This method is not used in the UserSpice code, but it is basically checking if
a user exists and can handle 3 types of input.
1. Integer for user id
2. Email
3. String for username
Passing any of those values will return true if a user matching that criteria exists
<?php $check = $user->find(2); ?>
<?php $check = $user->find('bob@aol.com'); ?>
and
<?php $check = $user->find('admin'); ?>
are all valid inputs.