return ErrFormat
	}

	return nil
}

func readDataDescriptor(r io.Reader, f *File) error {
	var buf [dataDescriptorLen]byte
	// The spec says: "Although not originally assigned a
	// signature, the value 0x08074b50 has commonly been adopted
	// as a signature value for the data descriptor record.
	// Implementers should be aware that ZIP files may be

	ctxSwitch
	ctxTypeSwitch
	ctxFile
	ctxDecl
	ctxSpec
	ctxDefer
	ctxCall  // any function call other than ctxCall2
	ctxCall2 // function call whose result is assigned to two variables
	ctxSelector
)

// walk walks the AST x, calling visit(f, x, context) for each node.
func (f *File) walk(x interface{}, context astContext, visit func(*File, interface{}, astContext)) {