Custom Value after SimpleSchema validate, but before insert?

help
1

I base on SimpleSchema .
I would like to Custom Value after validate schema, but before insert.
I tried

  score: {
    type: Number,
    autoValue() {
      // Custom number to decimal after validate, but before insert
      return Decimal(this.value) // Don't work
    },
  },
------------------ 
Student.insert({score: 123456.789.....})

Please help me