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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 source(self):
 """Return the source code for the definition."""

        full_src = self._source[self._slice]

        def is_empty_or_comment(line):
            return line.strip() == '' or line.strip().startswith('#')

        filtered_src = dropwhile(is_empty_or_comment, reversed(full_src))
        return ''.join(reversed(list(filtered_src)))