Using MechanicalSoup, does one have to set values for hidden fields in a form as well? Or can we just ignore them?
Here is their code in the HTML form:
<input type="hidden" name="details[sid]" />
<input type="hidden" name="details[page_num]" value="1" />
<input type="hidden" name="details[page_count]" value="1" />
<input type="hidden" name="details[finished]" value="0" />
<input type="hidden" name="form_build_id" value="form-OoBDi0_aQvgHZN-Iyc" />
<input type="hidden" name="form_id" value="webform_client_form_337" />
<input type="hidden" name="honeypot_time" value="1519679330|-x8kCHBe6qh7E" />
Hidden fields are typically used internally by the website you're browsing: they are generated with a value, and this value is sent together with non-hidden fields when you submit the form.
MechanicalSoup does what you expect here: it sends the values of hidden fields when you submit the form, so essentially you don't have to care about them: their value will be set by the website you're visiting, and then taken into account by MechanicalSoup just like a normal browser.
You shouldn't need to modify their value, because when using the website with a real browser, the user has no simple way to set a value (that's the point of hiding the fields ...).