# insert method

StringBuilder insert(

1. int index,
2. String str

)

Inserts a string at the specified index.

`index` the index at which to insert `str` the string to insert Returns this StringBuilder for method chaining

## Implementation

    StringBuilder insert(int index, String str) {
      String current = _buffer.toString();
      if (index < 0 || index > current.length) {
        throw RangeError('Index out of range: $index');
      }

      String before = current.substring(0, index);
      String after = current.substring(index);

      _buffer.clear();
      _buffer.write(before);
      _buffer.write(str);
      _buffer.write(after);

      return this;
    }