anchor.diff:    * Returns the larger of two numbers.
     *
     * Returns NaN if either argument is NaN.
  -  * The larger of [:-0.0:] and [:0.0:] is [:0.0:]. If the arguments are
  +  * The larger of `-0.0` and `0.0` is `0.0`. If the arguments are
     * otherwise equal (including int and doubles with the same mathematical value)
     * then it is unspecified which of the two arguments is returned.
     */
  
positive.code:   * Returns the lesser of two numbers.
    *
    * Returns NaN if either argument is NaN.
    * The lesser of [:-0.0:] and [:0.0:] is [:-0.0:].
    * If the arguments are otherwise equal (including int and doubles with the
    * same mathematical value) then it is unspecified which of the two arguments
    * is returned.
  
negative.code: /**
   * Converts [x] to a double and returns the natural exponent, [E],
   * to the power [x].
   *
   * Returns NaN if [x] is NaN.
   */
  external double exp(num x);
  
  /**
   * Converts [x] to a double and returns the natural logarithm of the value.
   *
   * Returns negative infinity if [x] is equal to zero.
   * Returns NaN if [x] is NaN or less than zero.
   */
  