code: def _get_columns(h5group):
      
      columns = set()
      for name in sorted(h5group):
          if (not isinstance(h5group[name], h5py.Dataset) or
                  name == 'template_boundaries'):
              continue
          if name.endswith('_template') and name[:-9] in columns:
              continue
          columns.add(name)
      return columns - META_COLUMNS
docs: Find valid column names from a PyCBC HDF5 Group
  
      Returns a `set` of names.