find_ivars

# File ext/psych/lib/psych/visitors/yaml_tree.rb, line 454
      def find_ivars target
        begin
          loc = target.method(:to_yaml_properties).source_location.first
          unless loc.start_with?(Psych::DEPRECATED) || loc.end_with?('rubytypes.rb')
            if $VERBOSE
              warn "#{loc}: to_yaml_properties is deprecated, please implement \"encode_with(coder)\""
            end
            return target.to_yaml_properties
          end
        rescue
          # public_method or source_location might be overridden,
          # and it's OK to skip it since it's only to emit a warning.
        end

        target.instance_variables
      end