protected function getMigrations($versionNumber = null)
{
$this->initialize();
if ($versionNumber === null) {
return $this->migrations;
}
if (!isset($this->migrations[$versionNumber])) {
throw new \InvalidArgumentException(sprintf('Migration "%s" was not found', $versionNumber), 1421667040);
}
return array($versionNumber => $this->migrations[$versionNumber]);
}