new (REXML::IOSource)

    # File src/rexml/source.rb, line 107
                    def initialize arg, block_size=500
                            @er_source = @source = arg
                            @to_utf = false
                            # READLINE OPT
                            # The following was commented out when IOSource started using readline
                            # to pull the data from the stream.
                            #@block_size = block_size
                            #super @source.read(@block_size)
                            @line_break = '>'
                            super @source.readline( @line_break )
                    end