CssTranslation constructor Null safety

CssTranslation(
  1. CssNumericValue x,
  2. CssNumericValue y,
  3. [CssNumericValue? z]
)

Implementation

factory CssTranslation(CssNumericValue x, CssNumericValue y,
    [CssNumericValue? z]) {
  if ((y is CssNumericValue) && (x is CssNumericValue) && z == null) {
    return CssTranslation._create_1(x, y);
  }
  if ((z is CssNumericValue) &&
      (y is CssNumericValue) &&
      (x is CssNumericValue)) {
    return CssTranslation._create_2(x, y, z);
  }
  throw new ArgumentError("Incorrect number or type of arguments");
}