Pandoc Lua filter matching all element types

How to write a Pandoc Lua filter with a function matching all elements despite of its node type?

With a Python panflute filter I would do it as follows:

# Python filter
from panflute import *

def action(elem, doc):
    debug(type(elem))

def main(doc=None):
    return run_filter(action, doc=doc)
    
if __name__ == "__main__":
    main()

With Lua I'd like to have somethig like the following:

-- Lua filter
function action(elem)
    print(pandoc.utils.type(elem))
end

return {
        {Inline = action},
        {Block = action},
        -- {* = action}, -- this is no valid Lua
        -- how many types must be added here to cover all the types?
    }

If every element type has to be explicitly added. Where can I get the List of all element types?

Lua filters support filtering on Inline, Block, Meta, and Pandoc elements. Thus this should work:

return {{
  Block = action,
  Inline = action,
  Meta = action,
  Pandoc = action,
}}

The docs could probably be a little clearer on that point.