# File lib/net/ssh/userauth/pageant.rb, line 180
          def read(n = nil)
            return nil unless @res
            if n.nil?
              start, @pos = @pos, @res.size
              return @res[start..-1]
            else
              start, @pos = @pos, @pos + n
              return @res[start, n]
            end
          end