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: issue1753.go
    path of file: ./repos/ebiten/internal/processtest/testdata
    
    the code of the file until where you have to start completion: // Copyright 2021 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0
    
func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
	return vec4(R, G, B, A)
}`))
		if err != nil {
			return err
		}

		op := &ebiten.DrawRectShaderOptions{}
		op.Blend = ebiten.BlendCopy
		op.Uniforms = map[string]any{
			"Dummy": float32(0),
			"R":     float32(0.5),
			"G":     float32(1),
			"B":     float32(0.5),
			"A":     float32(1),
		}
		g.dst.DrawRectShader(w, h, s, op)
		if got, want := g.dst.At(0, 0), (color.RGBA{0x80, 0xff, 0x80, 0xff}); got != want {
			return fmt.Errorf("phase: %d, got: %v, want: %v", g.phase, got, want)
		}

		return ebiten.Termination
	}

	return nil
}