# File lib/mechanize/chain/custom_headers.rb, line 6
 6:       def handle(ctx, params)
 7:         request = params[:request]
 8:         params[:headers].each do |k,v|
 9:           case k
10:           when :etag then request["ETag"] = v
11:           when :if_modified_since then request["If-Modified-Since"] = v
12:           else
13:             raise ArgumentError.new("unknown header symbol #{k}") if k.is_a? Symbol
14:             request[k] = v
15:           end
16:         end
17:         super
18:       end