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$s = 'anchor want this';
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if( $s =~ m/^.*?(anchor.*)$/ ){ $s = $1; }
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if( $s =~ m/^(.*?)anchor/ ){ my $bad = $1; $s =~ s/$bad//; }
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$s =~ s/^.*?anchor/anchor/;
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e.g., loops that utilize reverse, chop, split, ...