On 11-7-2015 12:26, candide wrote: >>>> 0 + not 0 > File "<stdin>", line 1 > 0 + not 0 > ^ > SyntaxError: invalid syntax >>>> > > > What is syntactically wrong with 0 + not 0? > I would say that the boolean operator 'not' cannot occur in an arithmetic expression. Maybe you meant to use the bitwise not: >>> 0 + ~0 -1 Irmen