NODE EXPLANATION
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m/ 'm/'
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^ the beginning of the string
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( group and capture to \1:
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\s* whitespace (\n, \r, \t, \f, and " ") (0
or more times (matching the most amount
possible))
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) end of \1
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( group and capture to \2 (optional
(matching the most amount possible)):
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( group and capture to \3:
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\S+ non-whitespace (all but \n, \r, \t,
\f, and " ") (1 or more times
(matching the most amount possible))
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) end of \3
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\s+ whitespace (\n, \r, \t, \f, and " ") (1
or more times (matching the most amount
possible))
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( group and capture to \4:
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\d+ digits (0-9) (1 or more times
(matching the most amount possible))
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) end of \4
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)? end of \2 (NOTE: because you are using a
quantifier on this capture, only the LAST
repetition of the captured pattern will be
stored in \2)
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\s* whitespace (\n, \r, \t, \f, and " ") (0 or
more times (matching the most amount possible))