Usage
testNegativeSkew(
  object,
  errormsg = paste(object$short_name, "is not negative skew")
)checkNegativeSkew(
  object,
  errormsg = paste(object$short_name, "is not negative skew")
)
assertNegativeSkew(
  object,
  errormsg = paste(object$short_name, "is not negative skew")
)