def get_event_attendees(self, event_id, status=None, changed_since=None, page=None):
    data = {}
    if status:
        data['status'] = status
    if changed_since:
        data['changed_since'] = changed_since
    if page:
        data['page'] = page
    return self.get("/events/{0}/attendees/".format(event_id), data=data)

from functools import wraps

def data(arg, optional=True):
    def func(f):
        @wraps(f)
        def _(self, event_id, *args, data=None, **kwargs):
            if data is None:
                data = {}
            # arg is either in kwargs OR args[0]
            if arg in kwargs:
                # found arg in kwargs
                data[arg] = kwargs[arg]
                del kwargs[arg]
            elif len(args) > 0:
                # found arg in args
                data[arg] = args[0]
                args = args[1:]
            elif not optional:
                # did not find arg and it is required
                raise TypeError("missing required argument {0}".format(arg))
            return f(self, event_id, *args, data=data, **kwargs)
        return _
    return func

@data("status")
@data("changed_since")
@data("page")
def get_event_attendees(self, event_id, data={}):
    return self.get("/events/{0}/attendees/".format(event_id), data=data)