'Check to see if the provided value is a valid choice'

def valid_value(self, value):

    text_value = force_text(value)
    for (k, v) in self.choices:
        if isinstance(v, (list, tuple)):
            for (k2, v2) in v:
                if ((value == k2) or (text_value == force_text(k2))):
                    return True
        elif ((value == k) or (text_value == force_text(k))):
            return True
    return False
