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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 render_list(self, cnt, unique=False, progress_callback=None, **kwargs):
        '''Return a list of generated strings.

        Args:
            cnt (int): length of list
            unique (bool): whether to make entries unique

        Returns:
            list.

        We keep track of total attempts because a template may
        specify something impossible to attain, like [1-9]{} with cnt==1000

        '''
        
        rendered_list = []
        i = 0
        total_attempts = 0
        while True:
            if i >= cnt:
                break
            if total_attempts > cnt * self.unique_attempts_factor:
                raise StringGenerator.UniquenessError(u"couldn't satisfy uniqueness")
            s = self.render(**kwargs)
            if unique:
                if not s in rendered_list:
                    rendered_list.append(s)
                    i += 1
            else:
                rendered_list.append(s)
                i += 1
            total_attempts += 1

            # Optionally trigger the progress indicator to inform others about our progress
            if progress_callback and callable(progress_callback):
                progress_callback(i, cnt)

        return rendered_list