showKeys = obj => {
  console.log();
  const keys = Object.keys(obj);
  const maxKeyLength = keys.reduce((max, key) => Math.max(max, key.length), 0);
  keys
    .filter(
      key => /^[a-z]/.test(key) && !obj[key].browserOnly && !obj[key].abstract
    )
    .sort()
    .forEach(key => {
      const description = obj[key].description;
      console.log(
        `    ${key.padEnd(maxKeyLength + 1)}${
          description ? `- ${description}` : ''
        }`
      );
    });
  console.log();
}
Dumps a sorted list of the enumerable, lower-case keys of some object
to `STDOUT`.
@param {Object} obj - Object, ostensibly having some enumerable keys
@ignore
@private