# File lib/http/form_data.rb, line 56
      def ensure_hash(obj)
        case
        when obj.nil?               then {}
        when obj.is_a?(Hash)        then obj
        when obj.respond_to?(:to_h) then obj.to_h
        else raise Error, "#{obj.inspect} is neither Hash nor responds to :to_h"
        end
      end