code: private function findUser()
      {
          $sql = sprintf(
              'SELECT * FROM %s WHERE %s = :identity',
              $this->getTableName(),
              $this->getIdentityColumn()
          );
          $stmt = $this->db->prepare($sql);
          $stmt->execute(array('identity' => $this->getIdentity()));
  
          // Explicitly setting fetch mode fixes
          // https://github.com/jeremykendall/slim-auth/issues/13
          return $stmt->fetch(PDO::FETCH_ASSOC);
      }
docs: Finds user to authenticate.
  
  @return array|null Array of user data, null if no user found