if not Web3.is_address(sys.argv[1]): print("❌ Invalid Ethereum ad…

[casks-mutters]

…dress.", file=sys.stderr) sys.exit(1) address = checksum(sys.argv[1])

Summary

The main CLI in app.py has a bit of duplicated and redundant validation:

• The Ethereum address is checked twice with Web3.is_address(...) (once before and once after to_checksum_address).
• The block range swap (if block_a > block_b) appears twice: once inside the try block and again immediately afterward, with two slightly different messages.

This PR simplifies the validation logic so that:

• The address is checked only once, then converted to checksum format.
• The block_a/block_b swap is performed in a single, clear place.

Changes

In app.py:

1. Address validation

   • Keep a single address validity check using Web3.is_address(sys.argv[1]).
   • If valid, convert to checksum form once and reuse it.
   • Remove the second Web3.is_address(address) check, which is redundant after checksumming.

2. Block range swap

   • Parse block_a and block_b in the try block.
   • Normalize their order exactly once (if block_a > block_b, swap and print a single message).
   • Remove the second if block_a > block_b branch after the try block.

Rationale

• Reduces duplication and makes the argument-parsing logic easier to read and maintain.
• Keeps CLI behavior the same (still validates address and ensures block_a <= block_b), but with less surprising repetition.
• Low-risk change touching only input validation.

Testing

• Run the following to ensure behavior is unchanged:

# Valid address, ordered blocks
python app.py 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 0x0 18000000 19000000

# Valid address, reversed blocks (should swap once and print a single swap message)
python app.py 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 0x0 19000000 18000000

# Invalid address (should error once, as before)
python app.py not_an_address 0x0 18000000 19000000