code: function decodeHexString( hex ) {
      const bytes = [];
      for(let i=0; i< hex.length-1; i+=2) {
          bytes.push(parseInt(hex.substr(i, 2), 16));
      }
      return Buffer.from(bytes)
  }
docs: /*
  Decode a hex string into a byte buffer.
  
  @param hex (String) a string of hex digits.
  
  Returns a buffer with the raw bytes