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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 read(self, size=None):
 """Read at most size bytes from the file. If size is not present or None, read all data until EOF is reached. """

        if self.closed:
            raise ValueError("I/O operation on closed file")

        buf = b""
        if self.buffer:
            if size is None:
                buf = self.buffer
                self.buffer = b""
            else:
                buf = self.buffer[:size]
                self.buffer = self.buffer[size:]

        if size is None:
            buf += self.fileobj.read()
        else:
            buf += self.fileobj.read(size - len(buf))

        self.position += len(buf)
        return buf