public function update( $args, $assoc_args ) {
		list( $object_id, $meta_key ) = $args;

		$meta_value = WP_CLI::get_value_from_arg_or_stdin( $args, 2 );
		$meta_value = WP_CLI::read_value( $meta_value, $assoc_args );

		$object_id = $this->check_object_id( $object_id );

		$meta_value = sanitize_meta( $meta_key, $meta_value, $this->meta_type );
		$old_value  = sanitize_meta( $meta_key, $this->get_metadata( $object_id, $meta_key, true ), $this->meta_type );

		if ( $meta_value === $old_value ) {
			WP_CLI::success( "Value passed for custom field '{$meta_key}' is unchanged." );
		} else {
			$meta_value = wp_slash( $meta_value );
			$success    = $this->update_metadata( $object_id, $meta_key, $meta_value );

			if ( $success ) {
				WP_CLI::success( "Updated custom field '{$meta_key}'." );
			} else {
				WP_CLI::error( "Failed to update custom field '{$meta_key}'." );
			}
		}

	}