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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 _from_dict(cls, _dict):
 """Initialize a DocStructure object from a json dictionary."""

        args = {}
        if 'section_titles' in _dict:
            args['section_titles'] = [
                SectionTitles._from_dict(x)
                for x in (_dict.get('section_titles'))
            ]
        if 'leading_sentences' in _dict:
            args['leading_sentences'] = [
                LeadingSentence._from_dict(x)
                for x in (_dict.get('leading_sentences'))
            ]
        return cls(**args)