code: def has_src_builder(self):
          
          try:
              scb = self.sbuilder
          except AttributeError:
              scb = self.sbuilder = self.find_src_builder()
          return scb is not None
docs: Return whether this Node has a source builder or not.
  
          If this Node doesn't have an explicit source code builder, this
          is where we figure out, on the fly, if there's a transparent
          source code builder for it.
  
          Note that if we found a source builder, we also set the
          self.builder attribute, so that all of the methods that actually
          *build* this file don't have to do anything different.