SET: Create a set of positive integers

syntax: SET(letter) or
SET(letter1, letter2) or
SET(letter, <filename>) or
SET(letter, size, integer 1, integer 2, integer 3 ...)

Creates a null set or a set containing a specified number of positive integers. <letter> is the letter variable ($A...$Z) containing the set. <size> is the size of the set as the number of positive integers it contains. Specifying only the set letter without other arguments creates a null set. Specifying a set letter followed by another set letter assigns the 2nd letter set <letter2> to the first letter set <letter1>. Specifying the set letter and a file name as the 2nd argument opens the file, reads the file contents and assigns the contents of the file into the set as set elements