'Return the callback dictionary.
:param method callback: The callback to call
:param bool one_shot: Remove this callback after it is called
:param object only_caller: Only allow one_caller value to call the
event that fires the callback.
:rtype: dict'

def _callback_dict(self, callback, one_shot, only_caller, arguments):

    value = {self.CALLBACK: callback, self.ONE_SHOT: one_shot, self.ONLY_CALLER: only_caller, self.ARGUMENTS: arguments}
    if one_shot:
        value[self.CALLS] = 1
    return value
