Loud Pumpkin with Circuit Playground

It's October. Pumpkins are filling the grocery stores. This means one thing: Halloween is coming!

I'm told that I'm supposed to wear a costume on Halloween. However, I'm too broke to buy an outfit for just one day, so I'm going to wear a colorful circuit board instead. This year, I'm going to become a pumpkin. Well, sorta.

The board is an Adafruit Circuit Playground Express. It packs 10 NeoPixel LEDs that can display any color, four sensors, and a few buttons. My code uses the microphone sensor to measure how loud is the environment. Based on measured sound pressure, it then lights up a number of NeoPixels to #ff7619 the "pumpkin color".

How to Print uint64_t in Arduino

The Arduino programming language looks like C++, but it is weird in its own way: there's no C++ standard library. In C++, you can print a variable to the debug console with std::cerr << x;. In Arduino, you have to write a function call: Serial.print(x);. I love that the Streaming library brings back the familiar syntax Serial << x; through some template and macro magic. But when it comes to a uint64_t variable, nothing works!

error: call of overloaded 'print(uint64_t&)' is ambiguous
   Serial.print(x);
                 ^

note: candidates are:
note: size_t Print::print(const __FlashStringHelper*) <near match>
note:   no known conversion for argument 1 from 'uint64_t {aka long long unsigned int}' to 'const __FlashStringHelper*'
note: size_t Print::print(const String&) <near match>
note:   no known conversion for argument 1 from 'uint64_t {aka long long unsigned int}' to 'const String&'