Python requests работа с checkbox

Как передать параметр checkbox с помощью Requests?

<div class="input "> 
                    <input type="checkbox" checked="checked" name="SEARCH_SPECIFIC_PRIMER" class="checkDef" id="SEARCH_SPECIFIC_PRIMER" defval="checked">
                    <label class="right inlinelabel" for="SPECIFICITY_CHECK">Enable search for primer pairs specific to the intended PCR template</label>            
                    <a class="helplink hiding" title="help" href="#" id="primerSpHl"><span>[?]</span></a>            
                    <p toggle="primerSpHl" class="helpbox hidden">
                        With this option on, the program will search the primers against the selected database and determine whether a primer pair can generate a PCR product on any targets in the database based on their matches to the targets and their orientations.  The program will return, if possible, only primer pairs that do not generate a valid PCR product on unintended sequences and are therefore specific to the intended template.  Note that the specificity is checked not only for the forward-reverse primer pair, but also for forward-forward as well as reverse-reverse primer pairs. 
                    </p>
                </div>

Я пытался передавать разные значения для name, типа data = {"SEARCH_SPECIFIC_PRIMER": 'on'}, вместо 'on' еще 1, true, ok и другие дурацкие варианты, но ничего не работает, сайт выдает ошибку. Как работать с checkbox'ами с помощью Requests?