def logout
      return true if self.session_token.blank?
      client.logout session_token
      self.session_token = nil
      true
    rescue => e
      false
    end
def logout
      return true if self.session_token.blank?
      client.logout session_token
      self.session_token = nil
      true
    rescue => e
      false
    end
Invalid the current session token for this logged in user.
 @return [Boolean] True/false if successful