Add example of explicitly setting History on ChatSession (#76)

Author: eliben

genai/example_test.go

@@ -178,6 +178,39 @@ func ExampleChatSession() {
 	printResponse(res)
 }
 
+// This example shows how to set the History field on ChatSession explicitly.
+func ExampleChatSession_history() {
+	ctx := context.Background()
+	client, err := genai.NewClient(ctx, option.WithAPIKey(os.Getenv("GEMINI_API_KEY")))
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer client.Close()
+	model := client.GenerativeModel("gemini-1.0-pro")
+	cs := model.StartChat()
+
+	cs.History = []*genai.Content{
+		&genai.Content{
+			Parts: []genai.Part{
+				genai.Text("Hello, I have 2 dogs in my house."),
+			},
+			Role: "user",
+		},
+		&genai.Content{
+			Parts: []genai.Part{
+				genai.Text("Great to meet you. What would you like to know?"),
+			},
+			Role: "model",
+		},
+	}
+
+	res, err := cs.SendMessage(ctx, genai.Text("How many paws are in my house?"))
+	if err != nil {
+		log.Fatal(err)
+	}
+	printResponse(res)
+}
+
 func ExampleEmbeddingModel_EmbedContent() {
 	ctx := context.Background()
 	client, err := genai.NewClient(ctx, option.WithAPIKey(os.Getenv("GEMINI_API_KEY")))