[] (RMail::Header)

    # File lib/rmail/header.rb, line 138
        def [](name_or_index)
          if name_or_index.kind_of? Fixnum
            temp = @fields[name_or_index]
            temp = temp.value unless temp.nil?
          else
            name = Field.name_canonicalize(name_or_index)
            result = detect { |n, v|
              if n.downcase == name then true else false end
            }
            if result.nil? then nil else result[1] end
          end
        end