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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 unstash_index(self, sync=False, branch=None):
 """Returns an unstash index if one is available."""


        stash_list = self.git_exec(['stash', 'list'], no_verbose=True)

        if branch is None:
            branch = self.get_current_branch_name()

        for stash in stash_list.splitlines():

            verb = 'syncing' if sync else 'switching'

            if (
                (('Legit' in stash) and
                 ('On {0}:'.format(branch) in stash) and
                 (verb in stash)
                 ) or
                (('GitHub' in stash) and
                 ('On {0}:'.format(branch) in stash) and
                 (verb in stash)
                 )
            ):
                return stash[7]