'Attempts to get a bucket from S3.
Works identically to ``S3Connection.get_bucket``, save for that it
will return ``None`` if the bucket does not exist instead of throwing
an exception.
:type bucket_name: string
:param bucket_name: The name of the bucket
:type headers: dict
:param headers: Additional headers to pass along with the request to
AWS.
:type validate: boolean
:param validate: If ``True``, it will try to fetch all keys within the
given bucket. (Default: ``True``)'

def lookup(self, bucket_name, validate=True, headers=None):

    try:
        bucket = self.get_bucket(bucket_name, validate, headers=headers)
    except:
        bucket = None
    return bucket
