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: headers.rs
    path of file: ./repos/aws-sdk-rust/sdk/aws-smithy-runtime-api/src/http
    
    the code of the file until where you have to start completion: /*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */

//! Types for HTTP headers

use crate::http::error::HttpError;
use http as http0;
use http0::header::Iter;
use http0::HeaderMap;
use std::borrow::Cow;
use std::fmt::Debug;
use std::str::FromStr;

/// An immut
    
fn header_value(value: MaybeStatic, panic_safe: bool) -> Result<HeaderValue, HttpError> {
    let header = match value {
        Cow::Borrowed(b) if panic_safe => {
            http0::HeaderValue::try_from(b).map_err(HttpError::invalid_header_value)?
        }
        Cow::Borrowed(b) => http0::HeaderValue::from_static(b),
        Cow::Owned(s) => {
            http0::HeaderValue::try_from(s).map_err(HttpError::invalid_header_value)?
        }
    };
    HeaderValue::from_http02x(header).map_err(HttpError::new)
}