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: mod.rs
    path of file: ./repos/p2panda/p2panda-rs/src/secret_group
    
    the code of the file until where you have to start completion: // SPDX-License-Identifier: AGPL-3.0-or-later

//! Create and moderate large secret groups to maintain key material for secure messaging.
//!
//! p2panda uses the [MLS] (Messaging Layer Security) protocol for group key negotiation to
//! establish sec
    
//! # fn main() -> Result<(), Box<dyn std::error::Error>> {
//! # use std::convert::TryFrom;
//! # use p2panda_rs::hash::Hash;
//! # use p2panda_rs::identity::KeyPair;
//! # use p2panda_rs::secret_group::{SecretGroup, SecretGroupMember, MlsProvider};
//! # let group_instance_id = Hash::new_from_bytes(&[1, 2, 3]);
//! // Define provider for cryptographic methods and key storage
//! let provider = MlsProvider::new();
//!
//! // Generate new Ed25519 key pair
//! let key_pair = KeyPair::new();
//!
//! // Create new group member based on p2panda key pair
//! let member = SecretGroupMember::new(&provider, &key_pair)?;
//!
//! // Create a secret group with member as the owner
//! let mut group = SecretGroup::new(&provider, &group_instance_id, &member)?;
//!
//! // Encrypt message
//! let ciphertext = group.encrypt(&provider, b"Secret Message")?;
//! # Ok(())
//! # }