Usage
testPositiveSkew(
  object,
  errormsg = paste(object$short_name, "is not positive skew")
)checkPositiveSkew(
  object,
  errormsg = paste(object$short_name, "is not positive skew")
)
assertPositiveSkew(
  object,
  errormsg = paste(object$short_name, "is not positive skew")
)