jodd-core/src/main/java/jodd/buffer/FastCharBuffer.java
@Override
	public FastCharBuffer append(final CharSequence csq, final int start, final int end) {
		for (int i = start; i < end; i++) {
			append(csq.charAt(i));
		}
		return this;
	}
@Override
	public FastCharBuffer append(final CharSequence csq, final int start, final int end) {
		for (int i = start; i < end; i++) {
			append(csq.charAt(i));
		}
		return this;
	}
Appends character sequence to buffer.