CSharpLox | platform compiler/interpreter .NET Standard implementation | Interpreter library

I have recently caught the language bug, and as part of my learning process I have begun working my way through the Crafting Interpreters book by Bob Nystrom and attempting to recreate the JLOX language interpreter in C#.

The "J" in JLOX refers to the sample code in the Book being implemented in Java.

In the "Working with Trees" and "A (Not Very) Pretty Printer" sections of the bok, Bob introduces the Visitor pattern as a solution to the "Expression Problem".

I have attempted to translate the Java code into C#, but am now stumped with the following compiler error:

"ASTPrinter.VisitBinaryExpr(Expression.Binary): No suitable method found to override" (click to see the image)

The two relevant code files are:

Expression.cs:

using System;