src/vs/editor/common/config/editorOptions.ts/EditorFontLigatures/constructor
class EditorFontLigatures:	constructor() {
		super(
			EditorOption.fontLigatures, 'fontLigatures', EditorFontLigatures.OFF,
			{
				anyOf: [
					{
						type: 'boolean',
						description: nls.localize('fontLigatures', "Enables/Disables font ligatures ('calt' and 'liga' font features). Change this to a string for fine-grained control of the 'font-feature-settings' CSS property."),
					},
					{
						type: 'string',
						description: nls.localize('fontFeatureSettings', "Explicit 'font-feature-settings' CSS property. A boolean can be passed instead if one only needs to turn on/off ligatures.")
					}
				],
				description: nls.localize('fontLigaturesGeneral', "Configures font ligatures or font features. Can be either a boolean to enable/disable ligatures or a string for the value of the CSS 'font-feature-settings' property."),
				default: false
			}
		);
	}