Returns the absolute value of the given numerical argument
Implemented by: dartmouth2, dartmouth4, ansimin, hptsb, decbasic, Altair, a2int, Applesoft, TI994, CBM, Atari, msatari, trs80, level2, trscolor, colormc, Sinclair, BBC, GWBASIC, MSX, bwbasic, bw32, ABasiC, QBasic, VBDOS, FreeBASIC, Gambas, ugBASIC, minibasicjs
With variations: Atom
Also written as: