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: prf_test.rs
    path of file: ./repos/webrtc/dtls/src/prf
    
    the code of the file until where you have to start completion: use super::*;
use crate::cipher_suite::Ciphe
    
fn test_pre_master_secret() -> Result<()> {
    let private_key: [u8; 32] = [
        0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e,
        0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d,
        0x3e, 0x3f,
    ];
    let private_key =
        NamedCurvePrivateKey::StaticSecretX25519(x25519_dalek::StaticSecret::from(private_key));
    let public_key = [
        0x9f, 0xd7, 0xad, 0x6d, 0xcf, 0xf4, 0x29, 0x8d, 0xd3, 0xf9, 0x6d, 0x5b, 0x1b, 0x2a, 0xf9,
        0x10, 0xa0, 0x53, 0x5b, 0x14, 0x88, 0xd7, 0xf8, 0xfa, 0xbb, 0x34, 0x9a, 0x98, 0x28, 0x80,
        0xb6, 0x15,
    ];

    let expected_pre_master_secret = vec![
        0xdf, 0x4a, 0x29, 0x1b, 0xaa, 0x1e, 0xb7, 0xcf, 0xa6, 0x93, 0x4b, 0x29, 0xb4, 0x74, 0xba,
        0xad, 0x26, 0x97, 0xe2, 0x9f, 0x1f, 0x92, 0x0d, 0xcc, 0x77, 0xc8, 0xa0, 0xa0, 0x88, 0x44,
        0x76, 0x24,
    ];

    let pre_master_secret = prf_pre_master_secret(&public_key, &private_key, NamedCurve::X25519)?;

    assert_eq!(
        expected_pre_master_secret, pre_master_secret,
        "PremasterSecret exp: {expected_pre_master_secret:?} actual: {pre_master_secret:?}"
    );

    Ok(())
}