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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_issue(self, branch):
 """ Gets the JIRA issue associated with the branch name. Returns None if no issue with this branch name. """

        if branch:
            try:
                issue = self.issue(branch, expand='changelog')
                return issue
            except jira.exceptions.JIRAError as ex:
                if ex.status_code == 404:
                    print "No JIRA issue found for branch %s" % branch
                else:
                    print str(ex)