'Checks for the existence of a file in Google Cloud Storage.
:param bucket: The Google cloud storage bucket where the object is.
:type bucket: string
:param object: The name of the object to check in the Google cloud
storage bucket.
:type object: string'

def exists(self, bucket, object):

    service = self.get_conn()
    try:
        service.objects().get(bucket=bucket, object=object).execute()
        return True
    except errors.HttpError as ex:
        if (ex.resp['status'] == '404'):
            return False
        raise
