# File lib/www/mechanize/chain/custom_headers.rb, line 7
 7:         def handle(ctx, params)
 8:           request = params[:request]
 9:           params[:headers].each do |k,v|
10:             case k
11:             when :etag then request.add_field("ETag", v)
12:             when :if_modified_since then request.add_field("If-Modified-Since", v)
13:             else
14:               raise ArgumentError.new("unknown header symbol #{k}") if k.is_a? Symbol
15:               request.add_field(k,v)
16:             end
17:           end
18:           super
19:         end