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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_list(self):
        '''Convert the source sequence to a list.

        Note: This method uses immediate execution.
        '''
        if self.closed():
            raise ValueError("Attempt to call to_list() on a closed Queryable.")

        # Maybe use with closable(self) construct to achieve this.
        if isinstance(self._iterable, list):
            return self._iterable
        lst = list(self)
        # Ideally we would close here. Why can't we - what is the problem?
        #self.close()
        return lst