Change instance variable numbers for line numbers instead of counter

还没有人认领这个 Issue。

Whenever we are creating a new instance of a variable or a fresh one, we keep the variable name and concatenate it with an incremental counter (e.g., a0, x1, y2).
A simple change would be to use the line number where this value was introduced, instead of the counter.
Example:

The error could be `#x_25 == #x_24 - 10` where `24` and `25` are the lines where these were introduced.
A question could be, if multiple vars are changed could we still use the same tactic? Lets try and make some tests to see.

首先定位创建新实例变量名的代码，以及针对生成名称的现有测试。检查在每个引入位置如何获得行号，然后添加测试，覆盖提议的基于行的名称，以及多个变量同时发生变化的情况；完成的标准是测试定义并确认预期的命名行为。

由索引模型根据 Issue 内容生成。