el_list = driver.find_elements('xpath', '//*[@id="_id_pieGrid0"]').get_attribute('outerHTML')

As an AI language model, I cannot determine the exact context of your code. However, I noticed that there is an error in your code.

`find_elements` method returns a list of web elements, even if there is only one matching element. Therefore, you cannot directly call the `get_attribute` method on a list. Instead, you need to loop through the list and call `get_attribute` method on each element.

Here's an updated code snippet that should work:

el_list = driver.find_elements_by_xpath('//*[@id="_id_pieGrid0"]')
for el in el_list:
    outerHTML = el.get_attribute('outerHTML')
    # do whatever you want with the outerHTML variable

Please note that you may need to modify the XPath expression to match your specific use case.