ask about fever (#1)

   if ( patient has fever ) {

      ask about sore throat and headache (#2)

      if ( patient has sore throat ) {

          say he has STREP THROAT

      } else {

          more nested if statements to deal
          with #3, #4 and #5

      }

   } else {

      ask about runny nose (#6)

      if ( patient has runny nose) {
        
           say that he has ALLERGIES

      } else {

         ask about sneezing (#7)

         if ( patient is sneezing ) {

            say he has a COLD

         } else {

            more code to deal with #8

         }
      }

   }