Function skewness

Skewness is a measure of symmetry of a distribution. Positive skewness means that the right tail is longer/fatter than the left tail. Negative skewness means the left tail is longer/fatter than the right tail. Zero skewness indicates a symmetrical distribution. Input must be an input range with elements implicitly convertible to double.

double skewness(T) (
  T data
)
if (doubleIterable!T);