'Set the annotation\'s default font as a dictionary of font properties
(at the moment only family and size are used).
>>> annotation.set_font({"family": "Helvetica", "size": 16})'

def set_font(self, font):

    check_type(font, dict)
    font = dict(font)
    if (self.__font != font):
        self.__font = font
        self.font_changed.emit(font)
