code: func findMidpoint(vertices ...*nmVertex) *nmVertex {
  	num := len(vertices) // this is what we divide by
  	vars := make([]float64, 0, num)
  
  	for i := 0; i < num; i++ {
  		sum := float64(0)
  		for _, v := range vertices {
  			sum += v.vars[i]
  		}
  		vars = append(vars, sum/float64(num))
  	}
  
  	return &nmVertex{
  		vars: vars,
  	}
  }
docs: // findMidpoint will find the midpoint of the provided vertices
  // and return a new vertex.