Suppose I have a form like this:
<form id='myform'>
Favorite colors?
<input type='checkbox' name='color' value='Green'>Green
<input type='checkbox' name='color' value='Blue'>Blue
<input type='checkbox' name='color' value='Red'>Red
<input type='submit' value='Submit'>
</form>
How do I use webtest's form library to test submitting multiple values?