Please show the employee first names and ids of employees who serve at least 10 customers.
return employees ;return customers #1 serve ;return number of  #2 for each  #1 ;return #1 where #3 is  at least 10 ;return first names of  #4 ;return ids of  #4 ;return #5 ,  #6
['select', 'project', 'group', 'comparative', 'project', 'project', 'union']