You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: config.rs
    path of file: ./repos/async-openai/async-openai/src
    
    the code of the file until where you have to start completion: //! Client configurations: [OpenAIConfig] for OpenAI, [AzureConfig] for Azure OpenAI Service.
use reqwest::header::{HeaderMap, AUTHORIZATION};
use secrecy::{ExposeSecret, Secret};
use serde::Deserialize;

/// Default v1 API base url
pub const OPENAI_API_BASE: &str = "https://api.openai.com/v1";
/// Name for organization header
pub const OPENAI_ORGANIZATION_HEADER: &str = "OpenAI-Org
    
    fn headers(&self) -> HeaderMap {
        let mut headers = HeaderMap::new();
        if !self.org_id.is_empty() {
            headers.insert(
                OPENAI_ORGANIZATION_HEADER,
                self.org_id.as_str().parse().unwrap(),
            );
        }

        headers.insert(
            AUTHORIZATION,
            format!("Bearer {}", self.api_key.expose_secret())
                .as_str()
                .parse()
                .unwrap(),
        );

        // hack for Assistants APIs
        // Calls to the Assistants API require that you pass a Beta header
        headers.insert(OPENAI_BETA_HEADER, "assistants=v1".parse().unwrap());

        headers
    }