src/EnvConfig.php
public function keyConvert(string $key) : string
    {
        $key = str_replace(ConfigKey::VALID_NON_ALPHANUM, '_', $key);
        if (!ConfigKey::validate($key)) {
            throw new InvalidArgumentException('Arg key contains invalid character(s).');
        }
        return $key;
    }
public function keyConvert(string $key) : string
    {
        $key = str_replace(ConfigKey::VALID_NON_ALPHANUM, '_', $key);
        if (!ConfigKey::validate($key)) {
            throw new InvalidArgumentException('Arg key contains invalid character(s).');
        }
        return $key;
    }
public function keyConvert ( string $ key ) : string { $ key = str_replace ( ConfigKey :: VALID_NON_ALPHANUM , '_' , $ key ) ; if ( ! ConfigKey :: validate ( $ key ) ) { throw new InvalidArgumentException ( 'Arg key contains invalid character(s).' ) ; } return $ key ; }
Replaces all legal non-alphanumeric chars with underscore.

@param string $key

@return string

@throws InvalidArgumentException
Replaces all legal non - alphanumeric chars with underscore .