code: @Override
  	public Appendable append(CharSequence csq, int start, int end) {
  		final int otherLen = end - start;
  		grow(this.len + otherLen);
  		for (int pos = start; pos < end; pos++) {
  			this.value[this.len + pos] = csq.charAt(pos);
  		}
  		this.len += otherLen;
  		return this;
  	}
docs: /*
  (non-Javadoc)
  @see java.lang.Appendable#append(java.lang.CharSequence, int, int)