How to use the autocorrect.utils.concat function in autocorrect

def _replaces(self):
        """tge"""
        return {concat(a, c, b[1:])
                for a, b in self.slices[:-1]
                for c in ALPHABET}

def _deletes(self):
        """th"""
        return {concat(a, b[1:])
                for a, b in self.slices[:-1]}

def _inserts(self):
        """thwe"""
        return {concat(a, c, b)
                for a, b in self.slices
                for c in ALPHABET}

def _transposes(self):
        """teh"""
        return {concat(a, reversed(b[:2]), b[2:])
                for a, b in self.slices[:-2]}