RK-A2

When user chooses a grade g and subject s, get file qna-cbse-g-s. This is of the following format:

Extend file format of qna-<board>-<grade>-<subject>.txt to:

#$Question: <question>
#$Answer: <answer>
#$Detailed QNAs: <detailed QNAs>
#$Detailed Answer: <detailed answer>
#$Question: <question>
#$Answer: <answer>
#$Detailed QNAs: <detailed QNAs>
#$Detailed Answer: <detailed answer>
....

Once the user answers the question correctly, ask "Correct answer. Would you like a detailed answer anyway (y/n)?
if y, give <detailed answer> and go on to the next question.

If the user answers wrongly, say "Not quite. Shall we go over the answer step by step (y/n)?"
If y, ask a detailed question. If answer is correct, say "Correct!" and ask next detailed question. If not, say "Not really. The answer is <give answer from detailed qna>"

Once you ask all detailed questions, ask "Would you like a detailed answer (y/n)?
if y, give <detailed answer> and go on to the next question.