*** Error: Non-boolean argument or result in 'b and c'.
*** Error: Non-boolean argument or result in 'b and c'.
*** Error: Non-boolean argument or result in '@ and c'.
*** Error: Non-boolean argument or result in 'b and @'.
*** Error: Non-boolean argument or result in 'true and c'.
*** Error: Non-boolean argument or result in 'b and true'.
*** Error: Non-boolean argument or result in 'false and c'.
*** Error: Non-boolean argument or result in 'b and false'.
