code: def _populate_issue(self, graph: TraceGraph, instance_id: int) -> None:
          
          instance = graph._issue_instances[instance_id]
          issue = graph._issues[instance.issue_id.local_id]
          self._populate_shared_text(graph, instance.message_id)
          self._populate_shared_text(graph, instance.filename_id)
          self._populate_shared_text(graph, instance.callable_id)
  
          self.add_issue_instance(instance)
          self.add_issue(issue)
  
          if instance_id in graph._issue_instance_fix_info:
              issue_fix_info = graph._issue_instance_fix_info[instance_id]
              self.add_issue_instance_fix_info(instance, issue_fix_info)
  
          for shared_text_id in graph._issue_instance_shared_text_assoc[instance_id]:
              shared_text = graph._shared_texts[shared_text_id]
              if shared_text_id not in self._shared_texts:
                  self.add_shared_text(shared_text)
              self.add_issue_instance_shared_text_assoc(instance, shared_text)
docs: Adds an issue to the trace graph along with relevant information
          pertaining to the issue (e.g. instance, fix_info, sources/sinks)
          The issue is identified by its corresponding instance's ID in the input
          trace graph.