app_test.py

import gradio as gr

with gr.Blocks() as block:
    textbox = gr.Textbox(label="Enter your text here")
    bttn = gr.Button()
    output = gr.Textbox(label="Output")

    def submit(input_data):
        return input_data + "Submitted"
    
    bttn.click(submit, inputs=[textbox], outputs=[output])

block.launch()