code: def Replace(self, **kw):
          
          try:
              kwbd = kw['BUILDERS']
          except KeyError:
              pass
          else:
              kwbd = BuilderDict(kwbd,self)
              del kw['BUILDERS']
              self.__setitem__('BUILDERS', kwbd)
          kw = copy_non_reserved_keywords(kw)
          self._update(semi_deepcopy(kw))
          self.scanner_map_delete(kw)
docs: Replace existing construction variables in an Environment
          with new construction variables and/or values.