src/JmesPath/Env.php
public static function createRuntime()
    {
        switch ($compileDir = getenv(self::COMPILE_DIR)) {
            case false: return new AstRuntime();
            case 'on': return new CompilerRuntime();
            default: return new CompilerRuntime($compileDir);
        }
    }
public static function createRuntime()
    {
        switch ($compileDir = getenv(self::COMPILE_DIR)) {
            case false: return new AstRuntime();
            case 'on': return new CompilerRuntime();
            default: return new CompilerRuntime($compileDir);
        }
    }
Creates a JMESPath runtime based on environment variables and extensions
available on a system.

@return callable