'Check if a prefix exists on Azure Blob storage.
:param container_name: Name of the container.
:type container_name: str
:param prefix: Prefix of the blob.
:type prefix: str
:param kwargs: Optional keyword arguments that
`BlockBlobService.list_blobs()` takes.
:type kwargs: object
:return: True if blobs matching the prefix exist, False otherwise.
:rtype bool'

def check_for_prefix(self, container_name, prefix, **kwargs):

    matches = self.connection.list_blobs(container_name, prefix, num_results=1, **kwargs)
    return (len(list(matches)) > 0)
