+// Expressions are somewhat of an exception, because some of their\r
+// grammar rules are recursive, so they have to be defined\r
+// in a single rule using Labels (https://github.com/antlr/antlr4/blob/master/doc/parser-rules.md#alternative-labels)\r
+// Because this results in a polymorphic type, getExpr for the base expression type\r
+// is always called and from there the polymorphic type is determined at runtime\r