Task: Sentence Expansion
Input (English): A voluntary association or union is a group of individuals who voluntarily enter into an agreement to form a body ( or organization ) to work together for a purpose .
Output (English): A voluntary group or union ( also sometimes called a voluntary organization , common-interest association , association , or society ) is a group of individuals who enter into an agreement , usually as volunteers , to form a body ( or organization ) to accomplish a purpose .