# Structs
ConfigureForDosVisitor implements both zoom's and hayes' visit method for Dos manufacturer.
ConfigureForUnixVisitor implements zoom's visit method for Unix manufacturer, unlike traditional visitor pattern, this class may selectively implement visit for other modems.
Hayes implements its accept method.
Zoom implements its accept method.
# Interfaces
AllModemVisitor interface extends all visitor interfaces.
HayesVisitor interface.
Modem interface.
ModemVisitor interface.
ZoomVisitor interface.