Add function in parser for checking if a word is reserved

parser/fspl/reserved.go

@@ -0,0 +1,13 @@
+package fsplParser
+
+func IsReserved (identifier string) bool {
+	switch identifier {
+	case "true", "false", "nil",
+		"if", "match", "switch",
+		"loop", "for",
+		"then", "in",
+		"break", "return":
+		return true
+	default: return false
+	}
+}