wp_get_speculative_loading_override( string $name ): string|null

158function wp_get_speculative_loading_override( string $name ): ?string {159	$value = null;160 161	// Check if the environment variable has been set, if `getenv` is available on the system.162	if ( function_exists( 'getenv' ) ) {163		$has_env = getenv( $name );164		if ( false !== $has_env ) {165			$value = $has_env;166		}167	}168 169	// Fetch the value from a constant, which overrides the environment variable.170	if ( defined( $name ) ) {171		$has_constant = constant( $name );172		if ( is_string( $has_constant ) ) {173			$value = $has_constant;174		}175	}176 177	return $value;178}