Regular Expressions 101

Explanation
Pro

Non-Capturing Group(?:.*?\K20[1-2]{1}[2-9]{1}){2}

{2}repeats the group contents below exactly 2 times:

.*?any character (except for line terminators), repeated any number of times

\Kresets the starting point of the reported match. Any previously consumed characters are no longer included in the final match

20the literal text 20

Character Class[1-2]{1}

{1}matches one character from the set below:

1-2one character from 1 (49₁₀) to 2 (50₁₀)

Character Class[2-9]{1}

{1}matches one character from the set below:

2-9one character from 2 (50₁₀) to 9 (57₁₀)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

25 tokens

(?:.*?\K20[1-2]{1}[2-9]{1}){2}

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