What's wrong with the jade mixin?

Question

Pug

mixin header_01(imageName)
  header
    div.container
      div.logo
        img(src="images/#{imageName}.png", alt="")
+header_01("logo");

gulp throws an error on this line +header_01("logo");. It is still not clear why the grate is put here img(src="images/#{imageName}.png", alt="")?

Answer 1

img(src=`images/${imageName}.png`, alt="")