private function checkVariableExists($variable, $type)
{
if ($type === 'env' && !getenv($variable) || $type === 'replacement' && !$this->rstore->arrayKeyExists($variable) || $type === 'variable' && !$this->vstore->arrayKeyExists($variable)) {
throw new \InvalidArgumentException(sprintf('Variable has not been defined as a `%s`: %s', $variable, $type));
}
return true;
}