(creating it if it didn't exist before), and C<quxx> as another value for
C<gorch>.
+B<NOTE> this is considered a legacy interface and care should be taken when
+using it. C<< scalar $c->req->param( 'foo' ) >> will return only the first
+C<foo> param even if multiple are present; C<< $c->req->param( 'foo' ) >> will
+return a list of as many are present, which can have unexpected consequences
+when writing code of the form:
+
+ $foo->bar(
+ a => 'b',
+ baz => $c->req->param( 'baz' ),
+ );
+
+If multiple C<baz> parameters are provided this code might corrupt data or
+cause a hash initialization error. For a more straightforward interface see
+C<< $c->req->parameters >>.
+
=cut
sub param {