code: def default_base_ant_pairs(self, context):
      
      k = 0 if context.cfg['auto_correlations'] == True else 1
      na = context.dim_global_size('na')
      gen = (i.astype(context.dtype) for i in np.triu_indices(na, k))
  
      # Cache np.triu_indices(na, k) as its likely that (na, k) will
      # stay constant much of the time. Assumption here is that this
      # method will be grafted onto a DefaultsSourceProvider with
      # the appropriate members.
      if self._is_cached:
          array_cache = self._chunk_cache['default_base_ant_pairs']
          key = (k, na)
  
          # Cache miss
          if key not in array_cache:
              array_cache[key] = tuple(gen)
  
          return array_cache[key]
  
      return tuple(gen)
docs: Compute base antenna pairs