Ankh.HTTP.Response.put_header
You're seeing just the function
put_header, go back to Ankh.HTTP.Response module for more information.
Link to this function
put_header(request, name, value)
Specs
put_header(t(), Ankh.HTTP.header_name(), Ankh.HTTP.header_value()) :: t()
See Ankh.HTTP.put_header/3.