code: def _read_columns_file(f):
      
      try:
          columns = json.loads(open(f, 'r').read(),
                               object_pairs_hook=collections.OrderedDict)
      except Exception as err:
          raise InvalidColumnsFileError(
              "There was an error while reading {0}: {1}".format(f, err))
  
      # Options are not supported yet:
      if '__options' in columns:
          del columns['__options']
  
      return columns
docs: Return the list of column queries read from the given JSON file.
  
      :param f: path to the file to read
      :type f: string
  
      :rtype: list of dicts