OP_PAIRCOMMIT python script

PairCommit.py

import hashlib

x1 = "Hello ".encode()
x2 = "World!".encode()
x1_size = len(x1)
x2_size = len(x2)

# CompactSize from https://github.com/btclib-org/btclib/blob/master/btclib/var_int.py
def compactsize(i: int) -> bytes:
    """Return the var_int bytes encoding of an integer."""
    if i < 0x00:
        raise f"negative integer: {i}"
    if i < 0xFD:  # 1 byte
        return bytes([i])
    if i <= 0xFFFF:  # 2 bytes
        return b"\xFD" + i.to_bytes(2, byteorder="little", signed=False)
    if i <= 0xFFFFFFFF:  # 4 bytes
        return b"\xFE" + i.to_bytes(4, byteorder="little", signed=False)
    if i <= 0xFFFFFFFFFFFFFFFF:  # 8 bytes
        return b"\xFF" + i.to_bytes(8, byteorder="little", signed=False)
    raise f"integer too big for var_int encoding: '{i}'"

# PairCommit
h = hashlib.new('sha256')
h.update("PairCommit".encode())
tag_hash = h.digest()

# OP_PAIRCOMMIT
h = hashlib.new('sha256')
h.update(tag_hash)
h.update(tag_hash)
h.update(compactsize(x1_size))
h.update(x1)
h.update(compactsize(x2_size))
h.update(x2)

print(h.hexdigest())