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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 from_buffer(self, buf):
 """ Identify the contents of `buf` """

        with self.lock:
            try:
                # if we're on python3, convert buf to bytes
                # otherwise this string is passed as wchar*
                # which is not what libmagic expects
                if isinstance(buf, str) and str != bytes:
                    buf = buf.encode('utf-8', errors='replace')
                return maybe_decode(magic_buffer(self.cookie, buf))
            except MagicException as e:
                return self._handle509Bug(e)