docstr: Return a modified URL with the username set.
  
  :param url: SQLAlchemy URL object
  :param impersonate_user: Flag indicating if impersonation is enabled
  :param username: Effective username
docstr_tok: ["Return","a","modified","URL","with","the","username","set",".",":","param","url",":","SQLAlchemy","URL","object",":","param","impersonate_user",":","Flag","indicating","if","impersonation","is","enabled",":","param","username",":","Effective","username"]
code: def get_url_for_impersonation(
      cls, url: URL, impersonate_user: bool, username: str | None
  ) -> URL:
      """
      Return a modified URL with the username set.
  
      :param url: SQLAlchemy URL object
      :param impersonate_user: Flag indicating if impersonation is enabled
      :param username: Effective username
      """
      # Do nothing and let update_impersonation_config take care of impersonation
      return url
  
imports: from __future__ import annotations
  import contextlib
  import logging
  import threading
  import time
  from typing import Any, TYPE_CHECKING
  import simplejson
  from flask import current_app
  from sqlalchemy.engine.reflection import Inspector
  from sqlalchemy.engine.url import URL
  from sqlalchemy.exc import NoSuchTableError
  from superset import db
  from superset.constants import QUERY_CANCEL_KEY, QUERY_EARLY_CANCEL_KEY, USER_AGENT
  from superset.databases.utils import make_url_safe
  from superset.db_engine_specs.base import BaseEngineSpec
  from superset.db_engine_specs.exceptions import SupersetDBAPIConnectionError
  from superset.db_engine_specs.presto import PrestoBaseEngineSpec
  from superset.models.sql_lab import Query
  from superset.superset_typing import ResultSetColumnType
  from superset.utils import core
label_desc: Use image node_id 3 for calling the TrinoEngineSpec obj's underlying member method code with example usage: obj.get_url_for_impersonation(cls, url, impersonate_user, username) and returns: url