UTF-32 sandbox (encode)

Step-by-step breakdown

1. 01

   Pick the endianness

   The low-order byte comes first (Little Endian). The 4 bytes are written in reverse order from the number.

   Little Endian (LE)
2. 02

   Convert to 32-bit binary

   UTF-32 always uses 32 bits, regardless of the code point.
   Code point U+1F389 fits in at most 21 significant bits (Unicode caps at U+10FFFF), so the 11 high bits are always zero.
   This padding is what makes UTF-32 simple: no format to guess, no marker, just the code point in its 32 bits.

   00000000000000011111001110001001
3. 03

   Convert to hexadecimal

   Split the binary into 4 packets of 8 bits, then write each packet in hex.
   The order of the 4 bytes depends on the chosen endianness.

   0x89 0xF3 0x01 0x00