def encoding_for_bars(*bars)
      wide, narrow, space = wide_encoding, narrow_encoding, space_encoding
      bars.flatten.inject '' do |enc,bar|
        enc + (bar == WIDE ? wide : narrow) + space
      end
    end
def encoding_for_bars(*bars)
      wide, narrow, space = wide_encoding, narrow_encoding, space_encoding
      bars.flatten.inject '' do |enc,bar|
        enc + (bar == WIDE ? wide : narrow) + space
      end
    end
Generate encoding for an array of W,N