Which engineers have never visited to maintain the assets? List the engineer first name and last name.
return engineers ;return #1 who  have  visited to maintain assets ;return #1 besides  #2 ;return first name  of  #3 ;return last name  of  #3 ;return #4 ,  #5
['select', 'filter', 'discard', 'project', 'project', 'union']