code: def cdx_load(sources, query, process=True):
      
      cdx_iter = create_merged_cdx_gen(sources, query)
  
      # page count is a special case, no further processing
      if query.page_count:
          return cdx_iter
  
      cdx_iter = make_obj_iter(cdx_iter, query)
  
      if process and not query.secondary_index_only:
          cdx_iter = process_cdx(cdx_iter, query)
  
      custom_ops = query.custom_ops
      for op in custom_ops:
          cdx_iter = op(cdx_iter, query)
  
      if query.output == 'text':
          cdx_iter = cdx_to_text(cdx_iter, query.fields)
      elif query.output == 'json':
          cdx_iter = cdx_to_json(cdx_iter, query.fields)
  
      return cdx_iter
docs: merge text CDX lines from sources, return an iterator for
      filtered and access-checked sequence of CDX objects.
  
      :param sources: iterable for text CDX sources.
      :param process: bool, perform processing sorting/filtering/grouping ops