Function   Syntax   Returns 
And   a && b   If a is false, a is returned and b is not evaluated. Otherwise, b is returned. 
Or   a  b   If a is true, a is returned and b is not evaluated. Otherwise, b is returned. 
Not   ! a   Returns 0 if a is true, 1 otherwise. 
Ifelse   a ? b : c   If a is true, b is returned and c is not evaluated. Otherwise c is returned and b is not evaluated. 
