docs: def varintSize(value):
    """Compute the size of a varint value."""
    if value <= 0x7f: return 1
    if value <= 0x3fff: return 2
    if value <= 0x1fffff: return 3
    if value <= 0xfffffff: return 4
    if value <= 0x7ffffffff: return 5
    if value <= 0x3ffffffffff: return 6
    if value <= 0x1ffffffffffff: return 7
    if value <= 0xffffffffffffff: return 8
    if value <= 0x7fffffffffffffff: return 9
    return 10