Delete a file.
        
        Parameters:
            * id: The Puush ID of the file to delete.

def delete(self, id):
        """Delete a file.
        
        Parameters:
            * id: The Puush ID of the file to delete.
        """
        res = self._api_request('del', data={'i': id})[0]
        if res[0] == '-1':
            raise PuushError("File deletion failed.")