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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def detach(self, attachments):
 """Remove an attachment, or a list of attachments, from this item. If the item has already been saved, the attachments will be deleted on the server immediately. If the item has not yet been saved, the attachments will simply not be created on the server the item is saved. Removing attachments from an existing item will update the changekey of the item. """

        if not is_iterable(attachments, generators_allowed=True):
            attachments = [attachments]
        for a in attachments:
            if a.parent_item is not self:
                raise ValueError('Attachment does not belong to this item')
            if self.id:
                # Item is already created. Detach  the attachment server-side now
                a.detach()
            if a in self.attachments:
                self.attachments.remove(a)