public S readFrom(BitInputStream bis) throws IOException{
		if(isLeaf()){
			//System.out.print((char)(byte)(Byte)symbol);
			return symbol;
		}
		Boolean bit = bis.readBit();
		if(bit==null)
			return null;
		//else
		if(bit)
			return right.readFrom(bis);
		//else
		return left.readFrom(bis);
	}