The Echo Chamber Decompression

You are decoding a compressed transmission. The format is 'k{content}', where 'k' is a positive integer and 'content' is a string or another compressed block. Rules: 1. If 'k' is ODD, simply repeat the decoded 'content' k times. 2. If 'k' is EVEN, repeat the decoded 'content' k times, but REVERSE the content in every even-indexed repetition (1st repeat is normal, 2nd is reversed, 3rd is normal, etc.). Example: '2{AB}' - k=2 (even), content='AB'. - Repeat 1: 'AB', Repeat 2: 'BA'. - Result: 'ABBA'. Input: A single string of compressed data. Output: The fully decompressed string. Example: Input: 3{A2{B}} Output: ABBBABBBABBB (2{B} is even, so 'B' followed by 'B' reversed is 'BB'. Then 3 repeats of 'ABB').