python
from supertokens_python import init, InputAppInfo
from supertokens_python.recipe import passwordless
from supertokens_python.recipe.passwordless.interfaces import APIInterface, APIOptions, ConsumeCodePostOkResult
from typing import Union, Dict, Any

def override_passwordless_apis(original_implementation: APIInterface):
    original_consume_code_post = original_implementation.consume_code_post

    async def consume_code_post(pre_auth_session_id: str,
                                user_input_code: Union[str, None],
                                device_id: Union[str, None],
                                link_code: Union[str, None],
                                api_options: APIOptions,
                                user_context: Dict[str, Any]):
        # Access the custom_field parameter from the user_context dictionary
        custom_field = await api_options.request.json().get("custom_field")

        # First we call the original implementation of consume_code_post.
        response = await original_consume_code_post(pre_auth_session_id, user_input_code, device_id, link_code, api_options, user_context)

        # Post sign up response, we check if it was successful
        if isinstance(response, ConsumeCodePostOkResult):
            user = response.user
            if response.created_new_user:
                # TODO: post sign up logic
            else:
                # TODO: post sign in logic

        return response

    # Update the original implementation with the new consume_code_post function
    original_implementation.consume_code_post = consume_code_post
    return original_implementation

init(InputAppInfo(...))
passwordless.init({
    "override": {
        "apis": override_passwordless_apis
    }
})

custom_field = await api_options.request.json().get("custom_field")