'Add challenge to TLSSNI01 object to perform at once.
:param .KeyAuthorizationAnnotatedChallenge achall: Annotated
TLSSNI01 challenge.
:param int idx: index to challenge in a larger array'

def add_chall(self, achall, idx=None):

    self.achalls.append(achall)
    if (idx is not None):
        self.indices.append(idx)
