
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 the functions: ①$f(x)=2\sin(2x+ \frac{\pi}{3})$; ②$f(x)=2\sin(2x- \frac{\pi}{6})$; ③$f(x)=2\sin(\frac{1}{2}x+ \frac{\pi}{3})$; ④$f(x)=2\sin(2x- \frac{\pi}{3})$, among them, the function with the smallest positive period of $\pi$ and whose graph is symmetric about the line $x= \frac{\pi}{3}$ is \_\_\_\_\_\_.

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