1*ac2a7c1bSSadaf Ebrahimi{ 2*ac2a7c1bSSadaf Ebrahimi? : value, # Empty key 3*ac2a7c1bSSadaf Ebrahimi? explicit 4*ac2a7c1bSSadaf Ebrahimi key: value, 5*ac2a7c1bSSadaf Ebrahimisimple key : value, 6*ac2a7c1bSSadaf Ebrahimi[ collection, simple, key ]: value 7*ac2a7c1bSSadaf Ebrahimi} 8