System.print(123.abs)      // expect: 123
System.print((-123).abs)   // expect: 123
System.print(0.abs)        // expect: 0
System.print((-0).abs)     // expect: 0
System.print((-0.12).abs)  // expect: 0.12
System.print(12.34.abs)    // expect: 12.34