Dependency
Dependency对象通常不是直接创建的，而是在设置事件监听器时返回的。它包含事件监听器的配置数据，并且可以使用.then()、.success()和.failure()来设置依赖于当前事件监听器完成的其他事件监听器。
import gradio as gr
with gr.Blocks() as demo:
first_textbox = gr.Textbox()
second_textbox = gr.Textbox()
button = gr.Button("Submit")
dependency = button.click(lambda x: "Hello, " + x, first_textbox, second_textbox)
dependency.success(lambda: gr.Info("Greeting successful"), None, None)
dependency.failure(lambda: gr.Warning("Greeting failed"), None, None)
demo.launch()
