Check if error is not nil and panic with message if it is.

Kernighan's Bit Counting Algorithm.

Greatest Common Denominator.

Least Common Multiple.

Convert Advent of Code height 6 font letters to a string.

Read all lines from reader.

Slice of cardinal directions.

+X direction.

+Y direction.

-Y direction.

Verbose flag.

-X direction.

2-D Point.