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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 tell(self):
 """Returns the current position of write head. Examples --------- 0 16 32 48 64 80 """

        assert self.writable
        pos = ctypes.c_size_t()
        check_call(_LIB.MXRecordIOWriterTell(self.handle, ctypes.byref(pos)))
        return pos.value