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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_last_commit_message(self):
 """ Gets the last commit message on the active branch Returns None if not in a git repo """

        # Check if we are currently in a repo
        try:
            branch = self.active_branch
            return self.commit(branch).message
        except InvalidGitRepositoryError:
            print "Not in a git repo"
            return None