NODE                     EXPLANATION
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(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
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  (?<!                     look behind to see if there is not:
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    \d                       digits (0-9)
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  )                        end of look-behind
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  (?:                      group, but do not capture (1 or more times
                           (matching the most amount possible)):
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    [1-9]+                   any character of: '1' to '9' (1 or more
                             times (matching the most amount
                             possible))
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    -                        '-'
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  )+                       end of grouping
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  (?:                      group, but do not capture (at least 3
                           times (matching the most amount
                           possible)):
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    0-                       '0-'
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  ){3,}                    end of grouping
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  0                        '0'
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)                        end of grouping
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