
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given two lines $l_1: ax + by + 1 = 0$ ($a, b$ are not both zero) and $l_2: (a-2)x + y + a = 0$. If $b=0$ and $l_1 \perp l_2$, find the value of the real number $a$.

Present the answer in LaTex format: \boxed{Your answer}
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