anchor.diff:  }
   
   /// Calculate the factorial of 'n'.
  +///
   /// For more information read: https://en.wikipedia.org/wiki/Factorial
   num factorial(num n) {
     assert(n >= 0, 'Factorial is not defined for negative number n ($n)');
  
positive.code: 
  /// Calculates all [Vector2]s of a circumference.
  ///
  /// Circumference is created from a [center] and a [radius]
  /// Also semi circumference could be created, specifying its [angle] in radians
  /// and the offset start angle [offsetAngle] for this semi circumference.
  /// The higher the [precision], the more [Vector2]s will be calculated,
  /// achieving a more rounded arc.
  ///
  /// For more information read: https://en.wikipedia.org/wiki/Trigonometric_functions.
  
negative.code: }
  
  /// Calculates the binomial coefficient of 'n' and 'k'.
  ///
  /// For more information read: https://en.wikipedia.org/wiki/Binomial_coefficient
  num binomial(num n, num k) {
    assert(0 <= k && k <= n, 'k ($k) and n ($n) must be in range 0 <= k <= n');
  