code: def get_from_environment():
      '''
          Return the JavaScript runtime that is specified in EXECJS_RUNTIME environment variable.
          If EXECJS_RUNTIME environment variable is empty or invalid, return None.
      '''
      name = os.environ.get("EXECJS_RUNTIME", "")
      if not name:
          return None
  
      try:
          return _find_runtime_by_name(name)
      except exceptions.RuntimeUnavailableError:
          return Nonf get_from_environment():
      '''
          Return the JavaScript runtime that is specified in EXECJS_RUNTIME environment variable.
          If EXECJS_RUNTIME environment variable is empty or invalid, return None.
      '''
      name = os.environ.get("EXECJS_RUNTIME", "")
      if not name:
          return None
  
      try:
          return _find_runtime_by_name(name)
      except exceptions.RuntimeUnavailableError:
          return None
docs: Return the JavaScript runtime that is specified in EXECJS_RUNTIME environment variable.
          If EXECJS_RUNTIME environment variable is empty or invalid, return None.