data(product_test)
cross_cpct(product_test, mrset(a1_1 %to% a1_6))
# same result
cross_cpct(product_test, mrset_f(a1_))
# same result
cross_cpct(product_test, mrset_p("a1_"))
# same result
cross_cpct(product_test, mrset_t("a1_{1:6}"))
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