code: public void substring(StringValue target, int start, int end) {
  		target.setValue(this, start, end - start);
  	}
docs: Copies a substring of this string into the given target StringValue. The
  substring begins at the given <code>start</code> index and ends at <code>end - 1</code>.
  
  @param target The StringValue object to copy the substring to.
  @param start The beginning index, inclusive.
  @param end The ending index, exclusive.
  @exception IndexOutOfBoundsException
  Thrown, if the start is negative, or the end is larger than the length.