It may not be relevant with the sentence, but does the phrase "I dunno" has the same meaning as "I don't know"? Because I saw this phrase quite often in comic books.
Yes, the phrase "I dunno" is a contraction of "I don't know". "I dunno" is not grammatically correct, but is written to express the spoken form of "I dunno", which is a common contraction in spoken English.
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