This class provides an empty implementation of {@link ExprVisitor},
which can be extended to create a visitor which only needs to handle a subset
of the available methods.
@param Variant The return type of the visit operation. Use {@link void} for
operations with no return type.
This class provides an empty implementation of {@link ExprVisitor}, which can be extended to create a visitor which only needs to handle a subset of the available methods.
@param Variant The return type of the visit operation. Use {@link void} for operations with no return type.