Support element size for each dataset

[dian-lun-lin]

Sometimes, applications need to determine the element size of a given dataset to estimate its overall size and manage memory allocation effectively. It would be beneficial to offer a universal element_size function for each dataset, allowing users to obtain this information without delving into the specifics and performing manual calculations.

[markovamaria]

Hi! I'd like to work on this issue. Could someone with maintainer privileges assign it to me, or let me know the process for obtaining the necessary permissions?

[ibhati]

Granted.