H5Diterate

herr_t H5Diterate(void *  buf,  hid_t type_id,  hid_t space_id,
       H5D_operator_t op,  void *  operator_data)

Iterates over all elements in a dataset.

`buf`	Buffer containing the dataset data
`type_id`	Datatype identifier
`space_id`	Dataspace identifier
`op`	Callback function
`operator_data`	User data to pass to the callback

The return value of the last callback on success, negative on failure.