code: def set_attr(self, name, value):
          
          if not is_valid_name(name):
              raise ValueError("Invalid name '%s'" % name)
  
          if name in self.namespace:
              if name in self.refs:
                  if name in self.self_refs:
                      self.new_ref(name, value)
                  else:
                      raise KeyError("Ref '%s' cannot be changed" % name)
  
              elif name in self.cells:
                  if self.cells[name].is_scalar():
                      self.cells[name].set_value((), value)
                  else:
                      raise AttributeError("Cells '%s' is not a scalar." % name)
              else:
                  raise ValueError
          else:
              self.new_ref(name, value)
docs: Implementation of attribute setting
  
          ``space.name = value`` by user script
          Called from ``Space.__setattr__``