Calculate target hash for bitcoin mining

btc_calc_target.py

def calc_target(bits: str) -> bytes:
    """
    Decompress the target from a compact format.
    """
    bits = bytes.fromhex(bits)

    # Extract the parts.
    byte_length = bits[0] - 3
    significand = bits[1:]

    # Scale the significand by byte_length.
    target = significand + b"\x00" * byte_length

    # Fill in the leading zeros.
    target = b"\x00" * (32 - len(target)) + target

    return target