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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 IndexCapacity object from a json dictionary."""

        args = {}
        if 'documents' in _dict:
            args['documents'] = EnvironmentDocuments._from_dict(
                _dict.get('documents'))
        if 'disk_usage' in _dict:
            args['disk_usage'] = DiskUsage._from_dict(_dict.get('disk_usage'))
        if 'collections' in _dict:
            args['collections'] = CollectionUsage._from_dict(
                _dict.get('collections'))
        return cls(**args)