Reset the namespace by removing all names defined by the user.

def reset_namespace(self, warning=False, message=False):
        """Reset the namespace by removing all names defined by the user."""
        reset_str = _("Remove all variables")
        warn_str = _("All user-defined variables will be removed. "
                     "Are you sure you want to proceed?")
        kernel_env = self.kernel_manager._kernel_spec.env

        if warning:
            box = MessageCheckBox(icon=QMessageBox.Warning, parent=self)
            box.setWindowTitle(reset_str)
            box.set_checkbox_text(_("Don't show again."))
            box.setStandardButtons(QMessageBox.Yes | QMessageBox.No)
            box.setDefaultButton(QMessageBox.Yes)

            box.set_checked(False)
            box.set_check_visible(True)
            box.setText(warn_str)

            answer = box.exec_()

            # Update checkbox based on user interaction
            CONF.set('ipython_console', 'show_reset_namespace_warning',
                     not box.is_checked())
            self.ipyclient.reset_warning = not box.is_checked()

            if answer != QMessageBox.Yes:
                return

        try:
            if self._reading:
                self.dbg_exec_magic('reset', '-f')
            else:
                if message:
                    self.reset()
                    self._append_html(_("<br><br>Removing all variables..."
                                        "\n<hr>"),
                                      before_prompt=False)
                self.silent_execute("%reset -f")
                if kernel_env.get('SPY_AUTOLOAD_PYLAB_O') == 'True':
                    self.silent_execute("from pylab import *")
                if kernel_env.get('SPY_SYMPY_O') == 'True':
                    sympy_init = """
                        from __future__ import division
                        from sympy import *
                        x, y, z, t = symbols('x y z t')
                        k, m, n = symbols('k m n', integer=True)
                        f, g, h = symbols('f g h', cls=Function)
                        init_printing()"""
                    self.silent_execute(dedent(sympy_init))
                if kernel_env.get('SPY_RUN_CYTHON') == 'True':
                    self.silent_execute("%reload_ext Cython")
                self.refresh_namespacebrowser()

                if not self.external_kernel:
                    self.silent_execute(
                        'get_ipython().kernel.close_all_mpl_figures()')
        except AttributeError:
            pass