Given two strings, s1 and s2, determine whether any permutation of s1 appears as a contiguous substring within s2. In other words, return TRUE if s2 contains a substring that uses the same characters as s1, with the same frequencies, but possibly in a different order. Otherwise, FALSE.

Constraints:

• $1 \leq$ s1.length, s2.length $\leq 10^4$

• s1 and s2 consist of lowercase English letters.

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