+// test: echo -e '1\nsto (2)\n3\nsto (5, 7)\nsto(9)\ndisp' | calc.exe | grep -q '0 1 0 0 7 0 0 0 7 0'
+// test: echo -e '1+1 == 2' | calc.exe | grep -q '=> 1'
+// test: echo -e '1 + 1 == 2 - 0' | calc.exe | grep -q '=> 1'
+// test: echo -e '1 == 1 + 1 == 1' | calc.exe | grep -q '=> 0'
+// test: echo -e '1-cos(3*pi/4) != 0.5^-2' | calc.exe | grep -q '=> 1'
+// test: echo -e '1 >= 2' | calc.exe | grep -q '=> 0'
+// test: echo -e '2 >= 2' | calc.exe | grep -q '=> 1'
+// test: echo -e '1 <= 2' | calc.exe | grep -q '=> 1'
+// test: echo -e '2 <= 2' | calc.exe | grep -q '=> 1'
+// test: echo -e '1 > 2' | calc.exe | grep -q '=> 0'
+// test: echo -e '2 > 2' | calc.exe | grep -q '=> 0'
+// test: echo -e '1 < 2' | calc.exe | grep -q '=> 1'
+// test: echo -e '2 < 2' | calc.exe | grep -q '=> 0'
+// test: echo -e '1 == 1\n1 != 1\n1 >= 1\n1 <= 1\n1 > 1\n1 < 1\nquit' | calc.exe -v 3 | grep -q bye
+// 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