// Create a Python class for a bank account

### Short summary

// Create a Python class for a bank account

### Affected version or release

V.1

### Installation context

// Create a Python class for a bank account

### What happened?

_No response_

### Steps to reproduce

_No response_

### Expected behavior

_No response_

### Additional context

_No response_

The issue provides no file, entry point, test, or project area to start from. First locate where Python code for this request belongs and clarify the bank account class's required behavior; completion cannot be verified from the current issue text alone.

索引モデルが issue の本文から書いたものです。