deep_munge

# File actionpack/lib/action_dispatch/http/request.rb, line 257
    def deep_munge(hash)
      hash.each do |k, v|
        case v
        when Array
          v.grep(Hash) { |x| deep_munge(x) }
          v.compact!
          hash[k] = nil if v.empty?
        when Hash
          deep_munge(v)
        end
      end

      hash
    end