class_docstr: Base class for Jupyter applications
docstr: Start the whole thing
docstr_tok: ["Start","the","whole","thing"]
code: def start(self):
      """Start the whole thing"""
      if self.subcommand:
          os.execv(self.subcommand, [self.subcommand] + self.argv[1:])
          raise NoStart()
  
      if self.subapp:
          self.subapp.start()
          raise NoStart()
  
      if self.generate_config:
          self.write_default_config()
          raise NoStart()
  
imports: from __future__ import print_function
  from copy import deepcopy
  import logging
  import os
  import sys
  from traitlets.config.application import Application, catch_config_error
  from traitlets.config.loader import ConfigFileNotFound
  from traitlets import Unicode, Bool, List, observe
  from .utils import ensure_dir_exists
  from ipython_genutils import py3compat
  from .paths import jupyter_config_dir, jupyter_data_dir, jupyter_runtime_dir, jupyter_path, jupyter_config_path, allow_insecure_writes, issue_insecure_write_warning
label_desc: Use image node_id 15 for calling the JupyterApp obj's underlying member method code with example usage: obj.start() without return types