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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 get_previous_release(self):
 """Get the release ID of the deployment immediately before the "current" deployment, ``None`` if no previous release could be determined. This method performs two network operations. :return: The release ID of the release previous to the "current" release. :rtype: str """

        releases = self.get_releases()
        if not releases:
            return None

        current = self.get_current_release()
        if not current:
            return None

        try:
            current_idx = releases.index(current)
        except ValueError:
            return None

        try:
            return releases[current_idx + 1]
        except IndexError:
            return None