1. A method for grouping related program sequences in a plurality of groupable program flow documents for performing a task, said method comprising: providing a plurality of groupable program flow documents to be executed by a group program sequence engine; establishing, using a first code for grouping, one or more groups that can be formed between one or more related group-elements obtained from said plurality of groupable program flow documents; and executing, using said group sequence engine, said plurality of groupable program flow documents, wherein each group-element considered an ancestor group-element of a group established and validated by said first code is executed before executing a related group-element obtained from said group, and wherein said related group-element of said group is executed only once during execution of said plurality of groupable program flow documents for performing said task.