Usage
testLeptokurtic(
  object,
  errormsg = paste(object$short_name, "is not leptokurtic")
)checkLeptokurtic(
  object,
  errormsg = paste(object$short_name, "is not leptokurtic")
)
assertLeptokurtic(
  object,
  errormsg = paste(object$short_name, "is not leptokurtic")
)