docs: 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)