Define main entry point.
Define default method calling GENERATE-AST.
Use MAKE-INSTANCE for FIXNUM-LESS-AST.
Use MAKE-INSTANCE for FIXNUM-NOT-GREATER-AST.
Use MAKE-INSTANCE for FIXNUM-GREATER-AST.
Use MAKE-INSTANCE for FIXNUM-NOT-LESS-AST.
Use MAKE-INSTANCE for FIXNUM-EQUAL-AST.
Bug fix.
Use SECOND rather than CADR.