func NewCanvas(ctx *gg.Context, font string, lineWidth float64) *Canvas {
	if err := ctx.LoadFontFace(font, 20); err != nil {
		panic(err)
	}
	ctx.SetLineWidth(lineWidth)
	return &Canvas{ctx, font, lineWidth}
}
NewCanvas is a constructor method, which instantiates a new Canvas element.
package canvas
import (
	"math"
	"math/rand"
	"github.com/fogleman/gg"
)
type Canvas struct {
	*gg.Context
	font      string
	lineWidth float64
}
type Drawer interface {
	Draw(*Canvas)
}
const CellSize float64 = 20