header_add()

    # add or replace the 'type' header
    $webapp->header_add( -type => 'image/png' );

    - or -

    # add an additional cookie
    $webapp->header_add(-cookie=>[$extra_cookie]);

    The header_add() method is used to add one or more headers to the outgoing response headers. The parameters will eventuallly be passed on to the CGI.pm header() method, so refer to the CGI docs for exact usage details.

    Unlike calling header_props(), header_add() will preserve any existing headers. If a scalar value is passed to header_add() it will replace the existing value for that key.

    If an array reference is passed as a value to header_add(), values in that array ref will be appended to any existing values values for that key. This is primarily useful for setting an additional cookie after one has already been set.