Sippet.Message.get_and_update
You're seeing just the function
get_and_update
, go back to Sippet.Message module for more information.
Gets the value from key and updates it, all in one pass.
About the same as Map.get_and_update/3
except that this function actually
does not remove the key from the struct case the passed function returns
:pop
; it puts nil
for :start_line
, :body
and :target
ands %{}
for
the :headers
key.