Function params_ref:: insert

Insert elements

            iterator
insert(
    iterator before,
    std::initializer_list init);

This function inserts the params in an initializer-list before the specified position.

All iterators that are equal to `before` or come after are invalidated.

The strings referenced by the inputs must not come from the underlying url, or else the behavior is undefined.

Linear in `this->url().encoded_query().size()`.

Strong guarantee. Calls to allocate may throw.