Ankh.HTTP.Request.fetch_trailer_values

You're seeing just the function fetch_trailer_values, go back to Ankh.HTTP.Request module for more information.
Link to this function

fetch_trailer_values(request, trailer)

Specs

fetch_trailer_values(t(), Ankh.HTTP.header_name()) :: [Ankh.HTTP.header_value()]

See Ankh.HTTP.fetch_trailer_values/2.