import Foundation

private let numberFormatter: NumberFormatter = {
  let formatter = NumberFormatter()
  formatter.numberStyle = .decimal
  formatter.maximumFractionDigits = 2
  return formatter
}()

extension String.StringInterpolation {
  mutating func appendInterpolation(double: Double, fractionDigits: Int = 2) {
    let formatter = NumberFormatter()
    formatter.numberStyle = .decimal
    formatter.maximumFractionDigits = fractionDigits
    appendInterpolation(numberFormatter.string(from: NSNumber(value: double))!)
  }
}