+ // public $db
+ // A PDO database object for interaction.
+ //
+ // private $pwd_cost
+ // The cost parameter for use with PHP password_hash function.
+ //
+ // private $pwd_nonces
+ // The array of nonces to use for "peppering" passwords. For new hashes, the last one of those will be used.
+ // Generate a nonce with this command: |openssl rand -base64 48|
+ //
+ // function log($code, $additional_info)
+ // Log an entry for admin purposes, with a code and some additional info.
+ //
+ // function checkPasswordConstraints($new_password, $user_email)