run.py

import gradio as gr
import os
from time import sleep

css_file = os.path.join(os.path.dirname(__file__), "file.css")

def set_lang(language):
    print(language)
    return gr.Code(language=language)

def set_lang_from_path():
    sleep(1)
    return gr.Code(open(css_file).read(), language="css")

def code(language, code):
    return gr.Code(code, language=language)

io = gr.Interface(lambda x: x, "code", "code", api_name="predict")

with gr.Blocks() as demo:
    lang = gr.Dropdown(value="python", choices=gr.Code.languages)  # type: ignore
    with gr.Row():
        code_in = gr.Code(
            language="python",
            label="Input",
            value='def all_odd_elements(sequence):\n    """Returns every odd element of the sequence."""',
            show_line_numbers = False
        )
        code_out = gr.Code(label="Output", show_line_numbers = True)
    btn = gr.Button("Run")
    btn_two = gr.Button("Load File")

    lang.change(set_lang, inputs=lang, outputs=code_in)
    btn.click(code, inputs=[lang, code_in], outputs=code_out)
    btn_two.click(set_lang_from_path, inputs=None, outputs=code_out)
    io.render()

if __name__ == "__main__":
    demo.launch()