Change sign using the ch s key.
 
eg.Calculator
key
ch s
java.lang.Exception: can't do key: ch s
	at eg.Calculator$HP35.key(Calculator.java:79)
	at eg.Calculator.execute(Calculator.java:33)
	at fit.ColumnFixture.doRow(ColumnFixture.java:26)
	at fit.Fixture.doRows(Fixture.java:88)
	at fit.ColumnFixture.doRows(ColumnFixture.java:17)
	at fit.Fixture.doTable(Fixture.java:82)
	at fit.Fixture.doTables(Fixture.java:72)
	at eg.AllFiles.run(AllFiles.java:72)
	at eg.AllFiles.doFiles(AllFiles.java:51)
	at eg.AllFiles.doRow(AllFiles.java:42)
	at eg.AllCombinations.doCase(AllCombinations.java:46)
	at eg.AllCombinations.combinations(AllCombinations.java:32)
	at eg.AllCombinations.combinations(AllCombinations.java:37)
	at eg.AllCombinations.combinations(AllCombinations.java:37)
	at eg.AllCombinations.combinations(AllCombinations.java:37)
	at eg.AllCombinations.combinations(AllCombinations.java:27)
	at eg.AllCombinations.doTable(AllCombinations.java:19)
	at fit.Fixture.doTables(Fixture.java:72)
	at eg.ExampleTests.run(ExampleTests.java:26)
	at eg.ExampleTests.right(ExampleTests.java:37)
	at java.lang.reflect.Method.invoke(Native Method)
	at fit.TypeAdapter.invoke(TypeAdapter.java:85)
	at fit.TypeAdapter.get(TypeAdapter.java:75)
	at fit.Fixture.check(Fixture.java:223)
	at fit.ColumnFixture.check(ColumnFixture.java:60)
	at fit.ColumnFixture.doCell(ColumnFixture.java:44)
	at fit.Fixture.doCells(Fixture.java:100)
	at fit.Fixture.doRow(Fixture.java:94)
	at fit.ColumnFixture.doRow(ColumnFixture.java:24)
	at eg.ExampleTests.doRow(ExampleTests.java:68)
	at fit.Fixture.doRows(Fixture.java:88)
	at fit.ColumnFixture.doRows(ColumnFixture.java:17)
	at fit.Fixture.doTable(Fixture.java:82)
	at fit.Fixture.doTables(Fixture.java:72)
	at fit.WikiRunner.process(WikiRunner.java:17)
	at fit.FileRunner.run(FileRunner.java:22)
	at fit.WikiRunner.main(WikiRunner.java:10)

See AllPairsExample.