anchor.diff:  
   /// 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,
  +/// A circumference can be achieved by specifying a [center] and a [radius].
  +/// In addition, a semi-circle can be achieved by specifying its [angle] and an
  +/// [offsetAngle] (both in radians).
  +///
  +/// 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.
  
positive.code: }
  
  /// 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)');
  
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');
  