Python: More elegant way to add optional parameters to method call

This will seem trivial perhaps, but it is a condition that I run into fairly frequently and would like to find a more elegant way of writing this code. The method, while not terribly relevant to the question, takes a text value and an optional is_checked value to create a radio button (using dominate). In this case, I can't set 'checked' to None, or false - it either has to be there or not. It doesn't seem like I should have to write the 'input' line twice though, just to optionally add an argument.

def _get_radio_button(text: str, is_checked=False):

    with label(text, cls="radio-inline") as lbl:
        if is_checked:
            input(text, type="radio", name="optradio", checked='checked')
        else:
            input(text, type="radio", name="optradio")

    return lbl

This would be my second approach, but it is the same lines of code and less readable - though perhaps a tiny bit more DRY.

a = dict(type='radio', name='optradio')
if is_checked: 
    a['checked']='checked'
with label(text, cls="radio-inline") as lbl:
    input(text, **a)

Question: How can I handle this code case with the fewest lines possible without sacrificing readability?