get
获取一条数据
def get(self, hash_key, sort_key, timeout=0):
"""
Get value stored in <hash_key, sort_key>.
:param hash_key: (str) which hash key used for this API.
:param sort_key: (str) which sort key used for this API.
:param timeout: (int) how long will the operation timeout in milliseconds.
if timeout > 0, it is a timeout value for current operation,
else the timeout value specified to create the instance will be used.
:return: (tuple<error_types.code.value, str>) (code, value).
code: error_types.ERR_OK.value when data got succeed, error_types.ERR_OBJECT_NOT_FOUND.value when data not found.
value: data stored in this <hash_key, sort_key>
"""