What is the test for dismissing a Three Strikes prior?

A trial court, in exercising its discretion whether to dismiss a strike prior, must consider whether, "in light of the nature and circumstances of [a defendant's] present felonies and prior serious and/or violent felony convictions, and the particulars of [the defendant's] background, character, and prospects, the defendant may be deemed outside the [Three Strikes] scheme's spirit, in whole or in part, and hence should be treated as though he [or she] had not previously been convicted of one or more serious and/or violent felonies." (People v. Williams (1998) 17 Cal.4th 148, 161.)

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