src/vs/platform/theme/common/tokenClassificationRegistry.ts/TokenClassificationRegistry/registerTokenModifier
class TokenClassificationRegistry:	public registerTokenModifier(id: string, description: string, deprecationMessage?: string): void {
		if (!id.match(typeAndModifierIdPattern)) {
			throw new Error('Invalid token modifier id.');
		}

		const num = this.currentModifierBit;
		this.currentModifierBit = this.currentModifierBit * 2;
		const tokenStyleContribution: TokenTypeOrModifierContribution = { num, id, description, deprecationMessage };
		this.tokenModifierById[id] = tokenStyleContribution;

		this.tokenStylingSchema.properties[`*.${id}`] = getStylingSchemeEntry(description, deprecationMessage);
	}