new (REXML::IOSource)

    # File src/rexml/source.rb, line 116
                    def initialize(arg, block_size=500)
                            @er_source = @source = arg
                            @to_utf = false
          # FIXME
          # This is broken.  If the user puts in enough carriage returns, this can fail
          # to calculate the correct encoding.
          super @source.read( 100 )
                            @line_break = encode( '>' )
                    end