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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 fun_en_complete_func(self, client, findstart_and_base, base=None):
 """Invokable function from vim and neovim to perform completion."""

        if isinstance(findstart_and_base, list):
            # Invoked by neovim
            findstart = findstart_and_base[0]
            base = findstart_and_base[1]
        else:
            # Invoked by vim
            findstart = findstart_and_base
        return client.complete_func(findstart, base)