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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 to_function(var_instance, lineno=None):
 """ Converts a var_instance to a function one """

        assert isinstance(var_instance, SymbolVAR)
        from symbols import FUNCTION
        var_instance.__class__ = FUNCTION
        var_instance.class_ = CLASS.function
        var_instance.reset(lineno=lineno)
        return var_instance