First, a multi-form switching
driver.switch_to.frame (id / name) may take the form of a default name or id attribute directly.
If not available iframe id and name attribute, an iframe may be positioned through the first XPath, and then locate the object passed driver.switch_to.frame (positioning objects)
driver.switch_to.parent_frame () to return to previous form
switch_to.default_content () jump back to the outermost layer of the page
Second, the multi-window switch
driver.current_window_handle: get the current window handle
driver.window_handles: Get all window handle, returns a list
switch_to_window (handle): switching window function, parameter fill handle
