DBeaver declare statement for MySQL is failing

Question

I get a syntax error no matter how I write the syntax for the MySQL declare statement. I tried it on a single line. I tried leaving off the default. I've tried removing the @. I posted this question once and it was closed due to a similar question but the answers to that question do not answer this. The suggested syntax on those answers is what I'm following below but still get the error. I wrapped it in a procedure at the suggestion of someone on the last question I posted but I still get the error.

delimiter //
  create procedure CleanPCB()
     begin 
            declare @datasource varchar(10) default 'ABC';
  end //
delimiter ;