# Buggy code
def run_cell(self, code, cell_name, filename, run_cell_copy):
    """Run cell in current or dedicated client."""

    def norm(text):
        return remove_backslashes(to_text_string(text))

    self.run_cell_filename = filename

    # Select client to execute code on it
    client = self.get_client_for_file(filename)
    if client is None:
        client = self.get_current_client()

    is_internal_kernel = False
    if client is not None:
        # Internal kernels, use runcell
        if client.get_kernel() is not None and not run_cell_copy:
            line = to_text_string("{}('{}','{}')").format(
                to_text_string("runcell"),
                (to_text_string(cell_name).replace("\\", "\\\\").replace("'", r"\'")),
                norm(filename).replace("'", r"\'"),
            )
            is_internal_kernel = True

        # External kernels and run_cell_copy, just execute the code
        else:
            line = code.strip()

        try:
            if client.shellwidget._executing:
                # Don't allow multiple executions when there's
                # still an execution taking place
                # Fixes issue 7293
                pass
            elif client.shellwidget._reading:
                client.shellwidget._append_html(
                    _(
                        "<br><b>Exit the debugger before trying to "
                        "run a cell in this console.</b>\n<hr><br>"
                    ),
                    before_prompt=True,
                )
                return
            else:
                if is_internal_kernel:
                    client.shellwidget.silent_execute(
                        to_text_string('get_ipython().cell_code = """{}"""').format(
                            to_text_string(code).replace('"""', r"\"\"\"")
                        )
                    )
                self.execute_code(line)
        except AttributeError:
            pass
        self.visibility_changed(True)
        self.raise_()
    else:
        # XXX: not sure it can really happen
        QMessageBox.warning(
            self,
            _("Warning"),
            _(
                "No IPython console is currently available "
                "to run <b>{}</b>.<br><br>Please open a new "
                "one and try again."
            ).format(osp.basename(filename)),
            QMessageBox.Ok,
        )


# Traceback (SyntaxError)
runcell('','C:/Users/User/Desktop/test.py')
File "<ipython-input-26-0a3ec57e3b80>", line 4
dirname = ("C:\Users\User\test.py")
^
SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 2-3: truncated \UXXXXXXXX escape

# Fixed code
def run_cell(self, code, cell_name, filename, run_cell_copy):
    """Run cell in current or dedicated client."""

    def norm(text):
        return remove_backslashes(to_text_string(text))

    self.run_cell_filename = filename

    # Select client to execute code on it
    client = self.get_client_for_file(filename)
    if client is None:
        client = self.get_current_client()

    is_internal_kernel = False
    if client is not None:
        # Internal kernels, use runcell
        if client.get_kernel() is not None and not run_cell_copy:
            line = to_text_string("{}('{}','{}')").format(
                to_text_string("runcell"),
                (to_text_string(cell_name).replace("\\", "\\\\").replace("'", r"\'")),
                norm(filename).replace("'", r"\'"),
            )
            is_internal_kernel = True

        # External kernels and run_cell_copy, just execute the code
        else:
            line = code.strip()

        try:
            if client.shellwidget._executing:
                # Don't allow multiple executions when there's
                # still an execution taking place
                # Fixes issue 7293
                pass
            elif client.shellwidget._reading:
                client.shellwidget._append_html(
                    _(
                        "<br><b>Exit the debugger before trying to "
                        "run a cell in this console.</b>\n<hr><br>"
                    ),
                    before_prompt=True,
                )
                return
            else:
                if is_internal_kernel:
                    client.shellwidget.silent_execute(
                        to_text_string('get_ipython().cell_code = r"""{}"""').format(
                            to_text_string(code).replace('"""', r"\"\"\"")
                        )
                    )
                self.execute_code(line)
        except AttributeError:
            pass
        self.visibility_changed(True)
        self.raise_()
    else:
        # XXX: not sure it can really happen
        QMessageBox.warning(
            self,
            _("Warning"),
            _(
                "No IPython console is currently available "
                "to run <b>{}</b>.<br><br>Please open a new "
                "one and try again."
            ).format(osp.basename(filename)),
            QMessageBox.Ok,
        )