I read some examples either to open file/ set file view or to
use struct data type only. How if a developer wants to set file
view with struct data type (as file type)? I notice that mpi_set_view
requires parameters `MPI_Datatype etype, MPI_Datatype filetype.'
However, for struct data type, it has multiple elementary types
(ARRAY_OF_TYPES). How can a developer determine which data type is the
elementary type in view? In addition, is it necessary (or a must have
step) to set view if one decides to open file?