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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 require_group(self, name, overwrite=False):
 """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 -------- True """


        return self._write_op(self._require_group_nosync, name,
                              overwrite=overwrite)