Added a tokenizer

src/token/List.go

@@ -0,0 +1,17 @@
+package token
+
+import "strings"
+
+// List is a slice of tokens.
+type List []Token
+
+// String implements string serialization.
+func (list List) String() string {
+	builder := strings.Builder{}
+
+	for _, t := range list {
+		builder.WriteString(t.String())
+	}
+
+	return builder.String()
+}