This class provides an empty implementation of CoreListener,
which can be extended to create a listener which only needs to handle a subset
of the available methods.
This class provides an empty implementation of CoreVisitor,
which can be extended to create a visitor which only needs to handle a subset
of the available methods.
This class provides an empty implementation of ExpressionListener,
which can be extended to create a listener which only needs to handle a subset
of the available methods.
This class provides an empty implementation of ExpressionVisitor,
which can be extended to create a visitor which only needs to handle a subset
of the available methods.