src/vs/editor/contrib/snippet/snippetVariables.ts/ClipboardBasedVariableResolver/resolve
class ClipboardBasedVariableResolver:	resolve(variable: Variable): string | undefined {
		if (variable.name !== 'CLIPBOARD') {
			return undefined;
		}

		const clipboardText = this._readClipboardText();
		if (!clipboardText) {
			return undefined;
		}

		// `spread` is assigning each cursor a line of the clipboard
		// text whenever there the line count equals the cursor count
		// and when enabled
		if (this._spread) {
			const lines = clipboardText.split(/\r\n|\n|\r/).filter(s => !isFalsyOrWhitespace(s));
			if (lines.length === this._selectionCount) {
				return lines[this._selectionIdx];
			}
		}
		return clipboardText;
	}