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$ perl -Mre=debug -e 'qr/0+|1+/; Final program: ... 7: EXACT <1> (0) 9: END (0) minlen 1
$ perl -Mre=debug -e 'qr/(0)+|(1)+/' Compiling REx "(0)+|(1)+" ... 23: END (0) minlen 1 Freeing REx: "(0)+|(1)+"