contrib: Fix SyntaxWarning in Python base58 implementation #19287

In Python integers should be compared for equality (i == j), not identity (i is j). Recent versions of CPython 3.x emit a SyntaxWarning when they encounter this incorrect usage, e.g.

$ python3 base58.py 
base58.py:110: SyntaxWarning: "is" with a literal. Did you mean "=="?
  assert get_bcaddress_version('15VjRaDX9zpbA8LVnbrCAFzrVzN7ixHNsC') is 0
Tests passed

Concept ACK. As I understand it is should only be used to check for "pointer-equality" and IIRC the only built-in type where that is acceptable (and maybe recommended) to use is None.

Did you also check the functional test files and other python files in this repo for similar sharp edges?

Concept ACK. As I understand it is should only be used to check for "pointer-equality"

'is is roughly equivalent to comparing pointers in C. As an implementation detail of CPython (not PyPy or others) x is y actually compares memory addresses, because on CPython id(x) returns the memory address of x.

the only built-in type where that is acceptable (and maybe recommended) to use is None.

True 99% of the time, mainly because None is a singleton. There are a few, rare corner cases, e,g. using an object() as a sentinel value https://python-patterns.guide/python/sentinel-object/

Did you also check the functional test files and other python files in this repo for similar sharp edges?

I didn't. I will.

No other files matching '*.py' exhibit this problem.

I also did a brief eyeball scan. Overall the Python scripts/modules look okay. A few suggestions

• contrib/seeds/generate-seeds.py
  • could use https://docs.python.org/3/library/argparse.html for argument handling
  • could probably use https://docs.python.org/3/library/ipaddress.html for IP parsing
• contrib/seeds/makeseeds.py
  • could probably use https://docs.python.org/3/library/ipaddress.html for IP parsing
• contrib/linearize-data.py
  • could use https://docs.python.org/3/library/argparse.html for argument handling
• contrib/linearize-hashes.py
  • could use https://docs.python.org/3/library/argparse.html for argument handling
• contrib/devtools/copyright_header.py
  • could use https://docs.python.org/3/library/argparse.html for argument handling
• a few locations are not using a context manager to ensure files are closed.
• a few modules and scripts include some type annotations, this could be expanded

ACK 47b49a05eafddcaef373f70436d794e9f9f7495c

Post-merge ACK 47b49a05eafddcaef373f70436d794e9f9f7495c

Warm welcome as a contributor @moreati! Thanks for reviewing the Python code in the repo.