def save
      raise EntityModelIsNotPersistedError unless entity.persisted?

      if persisted?
        return false unless changed?
        update
      else
        create
      end

      @previously_changed = changes
      @changed_attributes.clear

      true
    end
def save
      raise EntityModelIsNotPersistedError unless entity.persisted?

      if persisted?
        return false unless changed?
        update
      else
        create
      end

      @previously_changed = changes
      @changed_attributes.clear

      true
    end
Saves model
 Performs +insert+ or +update+ sql query
 Method doesn't perform sql query if model isn't modified

 @return [TrueClass, FalseClass]