Insert params
<boost/url/params_encoded_ref.hpp>
iterator
insert(
    iterator before,
    param_pct_view const& p);
This function inserts a param before the specified position.
All iterators that are equal to before or come after are invalidated.
Linear in this->url().encoded_query().size().
Strong guarantee. Calls to allocate may throw. Exceptions thrown on invalid input.
| Name | Thrown on | 
|---|---|
| system_error | pcontains an invalid percent-encoding. | 
| Name | Description | 
|---|---|
| before | An iterator before which the param is inserted. This may be equal to end(). | 
| p | The param to insert. |