-- see http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP:Biquad
-- for a list of available types, see
-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR.DSP.Biquad.Type
-- see http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP:Biquad
-- for a list of available types, see
-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR.DSP.Biquad.Type