code: def get(using=None):
      """Return a browser launcher instance appropriate for the environment."""
      if _tryorder is None:
          with _lock:
              if _tryorder is None:
                  register_standard_browsers()
      if using is not None:
          alternatives = [using]
      else:
          alternatives = _tryorder
      for browser in alternatives:
          if "%s" in browser:
              # User gave us a command line, split it into name and args
              browser = shlex.split(browser)
              if browser[-1] == "&":
                  return BackgroundBrowser(browser[:-1])
              else:
                  return GenericBrowser(browser)
          else:
              # User gave us a browser name or path.
              try:
                  command = _browsers[browser.lower()]
              except KeyError:
                  command = _synthesize(browser)
              if command[1] is not None:
                  return command[1]
              elif command[0] is not None:
                  return command[0]()
      raise Error("could not locate runnable browser")
  
imports: import os
  import shlex
  import shutil
  import sys
  import subprocess
  import threading
  import warnings
label_desc: Use image node_id 2 for calling a global function with example usage: get(using) and returns: BackgroundBrowser, GenericBrowser, command, command