Answer to Exercise 19

| ANSWER TO EXERCISE 19
| Add the following lines, after the inclusion of `Grammar`:
    [ SayInsteadSub; "[To talk to someone, please type ~someone, something~
    or else ~ask someone about something~.]"; ];
    Extend "answer" replace * topic -> SayInstead;
    Extend "tell"   replace * topic -> SayInstead;
A slight snag is that this will throw out "nigel, tell me about the grunfeld defence'' (which the library will normally convert to an `Ask` action, but can't if the grammar for "tell'' is missing). To avoid this, you could (instead of making the above directives) `Replace` the `TellSub` routine (see Section 21) by the `SayInsteadSub` one.

Back to the exercise in section 16

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