Conventions used

There are a number of text conventions used throughout this book.

Code in text: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: “We then define an activate_buzzer() function.”

A block of code is set as follows:

    def timer_callback(self):
        if self.mqtt_message.should_draw_circle:
            self.vel_msg.linear.x = 1.0
            self.vel_msg.angular.z = 1.0
        else:
            self.vel_msg.linear.x = 0.0
            self.vel_msg.angular.z = 0.0
        self.publisher.publish(self.vel_msg)

Bold: Indicates a new term, an important word, or words that you see onscreen. For instance, words in menus or dialog boxes appear in bold. Here is an example: “We do so by clicking on the Menu icon in the Raspberry Pi taskbar, navigating to the Programming category, and selecting Thonny.”

Tips or important notes

Appear like this.