code: public function createContainerIfNotExists($containerName = '', $metadata = array())
      {
          if ( ! $this->containerExists($containerName)) {
              $this->createContainer($containerName, $metadata);
          }
      }
docs: Create container if it does not exist
  
  @param string $containerName Container name
  @param array  $metadata      Key/value pairs of meta data
  @throws BlobException