class Rack::Chunked::TrailerBody

will return.
Trailer header listing the headers that the trailers method
of trailer headers, and the rack response itself should have a
initialize must have a trailers method that returns a hash
sending Trailer headers. Note that the response body provided to
A body wrapper that emits chunked responses and also supports

def yield_trailers

Yield strings for each trailer header. 
def yield_trailers
  @body.trailers.each_pair do |k, v|
    yield "#{k}: #{v}\r\n"
  end
end