function insert( text, id, str ) {
	var before;
	var after;
	var begin;
	var end;

	begin = '// BEGIN: '+id;
	end = '// END: '+id;

	before = substringBefore( text, begin );
	after = substringAfter( text, end );

	return format( '%s// BEGIN: %s\n\n%s\n%s%s', before, id, str, end, after );
}
Inserts a compiled function into file content.

@private
@param {string} text - source content
@param {string} id - function identifier
@param {string} str - function string
@returns {string} updated content