fails:The $SAFE variable can be set to 1
fails:The $SAFE variable cannot be set to 2
fails:The $SAFE variable cannot be set to 3
fails:The $SAFE variable cannot be set to 4
fails:The $SAFE variable cannot be set to values below 0
fails:The $SAFE variable cannot be set to values above 4
fails:The $SAFE variable cannot be manually lowered
fails:The $SAFE variable can be read when default from Thread#safe_level
fails:The $SAFE variable can be read when modified from Thread#safe_level
fails(SAFE is unsupported):The $SAFE variable raises ArgumentError when set to values below 0
fails(SAFE is unsupported):The $SAFE variable is not Proc local
fails(SAFE is unsupported):The $SAFE variable is not lambda local
fails(SAFE is unsupported):The $SAFE variable is global like regular global variables
