php - Laravel 5.1 ignores any values inside env() -

i uisn glravel 5.1 , setting mail service mailgun. i've found services file contains lines following:

'mailgun' => [     'domain' => env('<domain>'),     'secret' => env('<key>'), ],

now reason, these values ignored as-is. however, if remove env() method above, works. have this:

'mailgun' => [     'domain' => '<domain>',     'secret' => '<key>', ],

can explain why is?

because

env('foo');

you asking content of "foo" constant defined in .env file. have constant in .env file named 'foo'?

ITEMscalal