Start working on rust compile step

crates/libjrpc/templates/Dart/base.dart

@@ -0,0 +1,52 @@
+class JRPCError extends Error {
+  String message;
+  JRPCError(this.message);
+
+  @override
+  String toString() => message;
+}
+
+int? int_fromJson(dynamic val) {
+  if (val == null) {
+    return null;
+  } else if (val is int) {
+    return val;
+  } else if (val is double) {
+    return val.toInt();
+  } else {
+    throw JRPCError("Not a number!");
+  }
+}
+
+double? double_fromJson(dynamic val) {
+  if (val == null) {
+    return null;
+  } else if (val is int) {
+    return val.toDouble();
+  } else if (val is double) {
+    return val;
+  } else {
+    throw JRPCError("Not a number!");
+  }
+}
+
+bool? bool_fromJson(dynamic val) {
+  if (val == null) {
+    return null;
+  } else if (val is bool) {
+    return val;
+  } else {
+    throw JRPCError("Not a bool!");
+  }
+}
+
+String? String_fromJson(dynamic val) {
+  if (val == null) {
+    return null;
+  } else if (val is String) {
+    return val;
+  } else {
+    return val.toString(); // TODO: Either this or error
+    // throw JRPCError("Not a string!");
+  }
+}