func (f *WorkFile) DropGoStmt() {
	if f.Go != nil {
		f.Go.Syntax.markRemoved()
		f.Go = nil
	}
}

// DropToolchainStmt deletes the toolchain statement from the file.
func (f *WorkFile) DropToolchainStmt() {
	if f.Toolchain != nil {
		f.Toolchain.Syntax.markRemoved()
		f.Toolchain = nil
	}
}

// AddGodebug sets the first godebug line for key to value,

}

// A Require is a single require statement.
type Require struct {
	Mod      module.Version
	Indirect bool // has "// indirect" comment
	Syntax   *Line
}

func (r *Require) markRemoved() {
	r.Syntax.markRemoved()
	*r = Require{}
}

func (r *Require) setVersion(v string) {
	r.Mod.Version = v

	if line := r.Syntax; len(line.Token) > 0 {
		if line.InBlock {

	}
	line.Token = tokens
}

// markRemoved modifies line so that it (and its end-of-line comment, if any)
// will be dropped by (*FileSyntax).Cleanup.
func (line *Line) markRemoved() {
	line.Token = nil
	line.Comments.Suffix = nil
}

// Cleanup cleans up the file syntax x after any edit operations.
// To avoid quadratic behavior, (*Line).markRemoved marks the line as dead