def each_capitalized_name  #:yield: +key+
    block_given? or return enum_for(__method__)
    @header.each_key do |k|
      yield capitalize(k)
    end
  end
Iterates through the header names in the header, passing
capitalized header names to the code block.

Note that header names are capitalized systematically;
capitalization may not match that used by the remote HTTP
server in its response.