Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_30 (partner VARCHAR, surface VARCHAR, championship VARCHAR)
### Question:
Who was the partner when the championship was us open on a hard surface?
### Answer:
SELECT partner FROM table_name_30 WHERE surface = "hard" AND championship = "us open"