function replace( start, stop, str ) {
		var i;
		for ( i = start; i < stop; i++ ) {
			tmp[ i ] = '';
		}
		if ( start === stop ) {
			str += tmp[ start ];
		}
		tmp[ start ] = str;
	}
Replaces a substring within the wrapped command.

@private
@param {NonNegativeInteger} start - start index
@param {NonNegativeInteger} stop - end index
@param {string} str - replacement string