code: def bucket(cls, bucket_name, connection=None):
          
          connection = cls.connection if connection == None else connection
  
  
          if bucket_name not in cls._buckets:
              connection = "{connection}/{bucket_name}".format(connection=connection, bucket_name=bucket_name)
  
              if cls.password:
                  cls._buckets[connection] = Bucket(connection, password=cls.password)
              else:
                  cls._buckets[connection] = Bucket(connection)
  
          return cls._buckets[connection]
docs: Gives the bucket from couchbase server.
  
          :param bucket_name: Bucket name to fetch.
          :type bucket_name: str
          :returns: couchbase driver's Bucket object.
          :rtype: :class:`couchbase.client.Bucket`
          :raises: :exc:`RuntimeError` If the credentials wasn't set.