code: def add_const_spec(self, const_spec):
          
          if const_spec.name in self.const_specs:
              raise ThriftCompilerError(
                  'Cannot define constant "%s". That name is already taken.'
                  % const_spec.name
              )
          self.const_specs[const_spec.name] = const_spec
docs: Adds a ConstSpec to the compliation scope.
  
          If the ConstSpec's ``save`` attribute is True, the constant will be
          added to the module at the top-level.