You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: example_burnin_test.go
    path of file: ./repos/gonum/stat/sampleuv
    
    the code of the file until where you have to start completion: // Copyright Â©2015 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sampleuv_test

import (
	"gonum.org/v1/gonum/stat/distuv"
	"gonum.org/v1/gonum/stat/sampleuv"
)

type ProposalDist struct {
	Sigma float64
}

func (p ProposalDist) ConditionalRand(y float64) float64 {
	return distuv.Normal{Mu: y, Sigma: p.Sigma
    
func ExampleMetropolisHastings_burnin() {
	n := 1000    // The number of samples to generate.
	burnin := 50 // Number of samples to ignore at the start.
	var initial float64
	// target is the distribution from which we would like to sample.
	target := distuv.Weibull{K: 5, Lambda: 0.5}
	// proposal is the proposal distribution. Here, we are choosing
	// a tight Gaussian distribution around the current location. In
	// typical problems, if Sigma is too small, it takes a lot of samples
	// to move around the distribution. If Sigma is too large, it can be hard
	// to find acceptable samples.
	proposal := ProposalDist{Sigma: 0.2}

	samples := make([]float64, n)
	mh := sampleuv.MetropolisHastings{Initial: initial, Target: target, Proposal: proposal, BurnIn: burnin}
	mh.Sample(samples)
}