module.exports = function isupper(c) {
  //      discuss at: https://locutus.io/c/ctype/isupper/
  // parity verified: C 23
  //     original by: Kevin van Zonneveld (https://kvz.io)
  //          note 1: Checks if the character is an uppercase letter (A-Z).
  //       example 1: isupper('A')
  //       returns 1: true
  //       example 2: isupper('a')
  //       returns 2: false
  //       example 3: isupper('5')
  //       returns 3: false

  c = (c + '').charAt(0)
  return /^[A-Z]$/.test(c)
}