getEffectiveLevel() {
    if (this.level) {
      return this.level;
    } else if (this.parent) {
      return this.parent.getEffectiveLevel();
    }
    goog.asserts.fail('Root logger has no level set.');
    return goog.log.Level.OFF;
  }
Returns the effective level of the logger based on its ancestors' levels.
@return {!goog.log.Level} The level.