code: func FodderAppend(a *Fodder, elem FodderElement) {
  	if FodderHasCleanEndline(*a) && elem.Kind == FodderLineEnd {
  		if len(elem.Comment) > 0 {
  			// The line end had a comment, so create a single line paragraph for it.
  			*a = append(*a, MakeFodderElement(FodderParagraph, elem.Blanks, elem.Indent, elem.Comment))
  		} else {
  			back := &(*a)[len(*a)-1]
  			// Merge it into the previous line end.
  			back.Indent = elem.Indent
  			back.Blanks += elem.Blanks
  		}
  	} else {
  		if !FodderHasCleanEndline(*a) && elem.Kind == FodderParagraph {
  			*a = append(*a, MakeFodderElement(FodderLineEnd, 0, elem.Indent, []string{}))
  		}
  		*a = append(*a, elem)
  	}
  }
docs: // FodderAppend appends to the fodder but preserves constraints.
  //
  // See FodderConcat below.