What was the burden of proving that appellant's gang was a "criminal street gang" within the meaning of section 186.4(d)?

^4. The People also had the burden of proving that appellant's gang, the Surenos, was a "criminal street gang" within the meaning of section 186.22(d). (Cf. Salazar v. Superior Court (2000) 83 Cal.App.4th 840, 846 ["The existence of a criminal street gang is unquestionably an element of the street gang enhancement"].) The People presented extensive expert testimony on this point. We have not summarized that evidence because appellant does not challenge its sufficiency. We have reviewed this testimony and we conclude it was sufficient to establish that the Surenos are a "criminal street gang" ( 186.22(d)).