How to use the radian.settings.radian_settings.completion_prefix_length function in radian

def get_completions(self, document, complete_event):
        word = document.get_word_before_cursor()
        prefix_length = settings.completion_prefix_length
        if len(word) < prefix_length and not complete_event.completion_requested:
            return

        latex_comps = list(get_latex_completions(document, complete_event))
        # only return latex completions if prefix has \
        if len(latex_comps) > 0:
            for x in latex_comps:
                yield x
            return

        for x in self.get_r_builtin_completions(document, complete_event):
            yield x
        for x in self.get_package_completions(document, complete_event):
            yield x

def get_completions(self, document, complete_event):
        word = document.get_word_before_cursor()
        prefix_length = settings.completion_prefix_length
        if len(word) < prefix_length and not complete_event.completion_requested:
            return

        latex_comps = list(get_latex_completions(document, complete_event))
        # only return latex completions if prefix has \
        if len(latex_comps) > 0:
            for x in latex_comps:
                yield x
            return

        for x in self.get_r_completions(document, complete_event):
            yield x
        for x in self.get_package_completions(document, complete_event):
            yield x

def get_reticulate_completions(document, complete_event):
    word = document.get_word_before_cursor()
    prefix_length = settings.completion_prefix_length
    if len(word) < prefix_length and not complete_event.completion_requested:
        return []

    glo = rcopy(rcall(("reticulate", "py_run_string"), "globals()"))
    loc = rcopy(rcall(("reticulate", "py_run_string"), "locals()"))
    try:
        script = jedi.Interpreter(
            document.text,
            column=document.cursor_position_col,
            line=document.cursor_position_row + 1,
            path="input-text",
            namespaces=[glo, loc]
        )
        return [
            Completion(
                text_type(c.name_with_symbols),