I installed Dancer2, placked up it and opened web page from localhost.

Everything is OK until here.

There is following info at manual:

The code block given to the route handler has to return a string which will be used as the content to render to the client.

It is clear for following example

get '/test1/:name' => sub {
    return "Hi there " . params->{name};
};

because it returns a string and when I write http://localhost:5000/test1/kadir to browser I see  Hi there kadir which is the string I expect to see

But next example is as follow:

get '/test2/:name' => sub {
    "Hey ".param('name').", welcome here!";
};

It does not return anything. Because there is no return keyword.

Despite this I see   Hi there kadir  when I write http://localhost:5000/test2/kadir

But above red background colored sentence says that it must return a value?

Next example is stranger:

get '/test3/:name' => sub {
    "Hello there, " . defined param('name')
                    ? param('name')
                    : "whoever you are!";
};

Again there is no return keyword. When I write http://localhost:5000/test3/kadir I see only kadir. But at test2 example, I saw all words despite there is no return keyword. So what is rule?

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