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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 set_contents(self, contents, encoding=None):
 """Sets the file contents and size and increases the modification time. Also executes the side_effects if available. Args: contents: (str, bytes, unicode) new content of file. encoding: (str) the encoding to be used for writing the contents if they are a unicode string. If not given, the locale preferred encoding is used. Raises: IOError: if `st_size` is not a non-negative integer, or if it exceeds the available file system space. """

        self.encoding = encoding
        changed = self._set_initial_contents(contents)
        if self._side_effect is not None:
            self._side_effect(self)
        return changed