docs: public StrBuilder insert(int index, CharSequence csq) {
  		if (null == csq) {
  			csq = "null";
  		}
  		int len = csq.length();
  		moveDataAfterIndex(index, csq.length());
  		if (csq instanceof String) {
  			((String) csq).getChars(0, len, this.value, index);
  		} else if (csq instanceof StringBuilder) {
  			((StringBuilder) csq).getChars(0, len, this.value, index);
  		} else if (csq instanceof StringBuffer) {
  			((StringBuffer) csq).getChars(0, len, this.value, index);
  		} else if (csq instanceof StrBuilder) {
  			((StrBuilder) csq).getChars(0, len, this.value, index);
  		} else {
  			for (int i = 0, j = this.position; i < len; i++, j++) {
  				this.value[j] = csq.charAt(i);
  			}
  		}
  		this.position = Math.max(this.position, index) + len;
  		return this;
  	}