+// test: echo -e 'mem (3)\nsto (4, pi)' | calc.exe | grep -q "invalid index"
+// test: echo -e 'disp' | calc.exe | grep -q "storage: 0 0 0 0 0 0 0 0 0 0"
+// test: echo -e 'sto (3, 10)\ndisp' | calc.exe | grep -q "storage: 0 0 10 0 0 0 0 0 0 0"
+// test: echo -e 'rcl (3)\ndisp' | calc.exe | grep -q "storage: 0 0 0 0 0 0 0 0 0 0"
+// test: echo -e 'inc (2)\ndisp' | calc.exe | grep -q "storage: 0 1 0 0 0 0 0 0 0 0"
+// test: echo -e 'dec (2)\ndisp' | calc.exe | grep -q "storage: 0 -1 0 0 0 0 0 0 0 0"