src/Compiler.php
protected function extractEnv($envs)
    {
        for ($env = null; $e = array_pop($envs);) {
            $e->parent = $env;
            $env = $e;
        }

        return $env;
    }
protected function extractEnv($envs)
    {
        for ($env = null; $e = array_pop($envs);) {
            $e->parent = $env;
            $env = $e;
        }

        return $env;
    }
protected function extractEnv ( $ envs ) { for ( $ env = null ; $ e = array_pop ( $ envs ) ; ) { $ e -> parent = $ env ; $ env = $ e ; } return $ env ; }
Convert env stack to singly linked list

@param array $envs

@return \Leafo\ScssPhp\Compiler\Environment
Convert env stack to singly linked list