XEts.get_and_update

You're seeing just the function get_and_update, go back to XEts module for more information.
Link to this function

get_and_update(tab, key, fun)

Specs

get_and_update(t(), any(), any()) :: any()

Get and update an item in the table.

iex> tab = XEts.new(:foo)|> XEts.put(:k, 2)
iex> XEts.get_and_update(tab, :k, & { &1, &1 + 1 })
{2, tab}