"An error that occurs due to an incorrectly written program. 
 An instance is thrown when an assertion fails, that is, 
 when a condition in an `assert` statement evaluates to 
 false at runtime.
 The assertion
     \"x must be positive\"
     assert (x>0);
 has almost the same effect as this `if` statement
     if (!x>0) {
         throw AssertionError(\"x must be positive\");
shared native class AssertionError(message)
        extends Throwable(message) {
    "A message describing the assertion that failed. In the
     case of an `assert` statement, it is the text specified
     by the `doc` annotation.
     Certain tools interpret this message as 
     markdown-formatted text."
    String message;