+// test: echo -e '(3 == 3) & (2 > 1)' | calc.exe | grep -q '=> 1'
+// test: echo -e '(3 == 4) & (2 > 1)' | calc.exe | grep -q '=> 0'
+// test: echo -e '(3 == 3) & (2 > 2)' | calc.exe | grep -q '=> 0'
+// test: echo -e '(3 == 4) & (2 > 2)' | calc.exe | grep -q '=> 0'
+// test: echo -e '(3 == 3) | (2 > 1)' | calc.exe | grep -q '=> 1'
+// test: echo -e '(3 == 4) | (2 > 1)' | calc.exe | grep -q '=> 1'
+// test: echo -e '(3 == 3) | (2 > 2)' | calc.exe | grep -q '=> 1'
+// test: echo -e '(3 == 4) | (2 > 2)' | calc.exe | grep -q '=> 0'
+// test: echo -e '!(3 == 4)' | calc.exe | grep -q '=> 1'
+// test: echo -e '!(3 == 3)' | calc.exe | grep -q '=> 0'
+// test: echo -e '1 & 1\n1 | 1\n!(1)\nquit' | calc.exe -v 3 | grep -q bye
+// test: echo -e '(3 == 3) & (4 > 2)' | calc.exe | grep -q '=> 1'
+// test: echo -e '3 == 3 & 4 > 2' | calc.exe | grep -q '=> 1'
+// test: echo -e '1 + quit' | calc.exe 2>&1 | grep -q error
+// test: echo -e 'cos (quit)' | calc.exe 2>&1 | grep -q error
+// test: echo -e '(quit)' | calc.exe 2>&1 | grep -q error