compute() is useful for several purposes. It's original
purpose is to send a request for data, which can then be processed by the
server and retrieved at a later time (via collect()).
Arguments
- x
- An object of class - data_request,- metadata_requestor- files_request(i.e. constructed using a pipe) or- query(i.e. constructed by- collapse())
- ...
- Arguments passed on to other methods 
