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: error.rs
    path of file: ./repos/polkadot/node/core/pvf/common/src
    
    the code of the file until where you have to start completion: // Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Polkadot.

// Polkadot is free software: you can redistribute it an
    
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		use InternalValidationError::*;
		match self {
			HostCommunication(err) =>
				write!(f, "validation: some communication error occurred with the host: {}", err),
			CouldNotOpenFile(err) =>
				write!(f, "validation: could not find or open compiled artifact file: {}", err),
			CpuTimeMonitorThread(err) =>
				write!(f, "validation: an error occurred in the CPU time monitor thread: {}", err),
			NonDeterministicPrepareError(err) => write!(f, "validation: prepare: {}", err),
		}
	}