'Rotate the list. The first client is moved to last position.
If maintain_index is True the current_index is adjusted,
such that the same client stays current and goes up in list.'

def rotate_up(self, maintain_index=True):

    if (len(self.clients) > 1):
        self.clients.append(self.clients.pop(0))
        if maintain_index:
            self.current_index -= 1
