code: def require_group(self, name, overwrite=False):
          
  
          return self._write_op(self._require_group_nosync, name,
                                overwrite=overwrite)
docs: Obtain a sub-group, creating one if it doesn't exist.
  
          Parameters
          ----------
          name : string
              Group name.
          overwrite : bool, optional
              Overwrite any existing array with given `name` if present.
  
          Returns
          -------
          g : zarr.hierarchy.Group
  
          Examples
          --------
          >>> import zarr
          >>> g1 = zarr.group()
          >>> g2 = g1.require_group('foo')
          >>> g3 = g1.require_group('foo')
          >>> g2 == g3
          True