How to view return value of Oracle stored function containing DML in PLSQL Developer?

Selecting the return value of an Oracle stored function that doesn't contain DML can be done by simply selecting the function:

select function_name() from dual;

If the function contains DML (in this case some inserts to log the arguments passed to the function), the above query is not allowed. (ORA-14551)

How can I select/view the return value of this function?

if I choose "test" in plsql developer, plsqldev produces something like:

declare
  -- Non-scalar parameters require additional processing 
  result xmltype;
begin
  -- Call the function
  result := find_person(as_surname => :as_surname,
                       as_given => :as_given,
                       ad_birth_date_from => :ad_birth_date_from,
                       ad_birth_date_to => :ad_birth_date_to,
                       as_gender => :as_gender);
end;

How can I view the value of the "result" variable?

select result from dual;

inside the begin/end block produces

ORA-06550: PLS-00428: an INTO clause is expected in this SELECT statement