Implemented struct parser

src/token/Tokenize_test.go

@@ -25,7 +25,7 @@ func TestFunction(t *testing.T) {
 }
 
 func TestKeyword(t *testing.T) {
-	tokens := token.Tokenize([]byte("assert if import else loop return switch"))
+	tokens := token.Tokenize([]byte("assert if import else loop return struct switch"))
 
 	expected := []token.Kind{
 		token.Assert,
@@ -34,6 +34,7 @@ func TestKeyword(t *testing.T) {
 		token.Else,
 		token.Loop,
 		token.Return,
+		token.Struct,
 		token.Switch,
 		token.EOF,
 	}