code: def build_remap_symbols(self, name_generator, children_only=None):
          
  
          replacement = name_generator(skip=(self._reserved_symbols))
          self.remapped_symbols[self.catch_symbol] = next(replacement)
  
          # also to continue down the children.
          for child in self.children:
              child.build_remap_symbols(name_generator, False)
docs: The children_only flag is inapplicable, but this is included as
          the Scope class is defined like so.
  
          Here this simply just place the catch symbol with the next
          replacement available.