#include "tensorstore/progress.h"
friend std::ostream&
tensorstore::CopyProgress::operator<<(std::ostream& os,
                                      
const CopyProgress& a);
template <typename Sink>
friend void
tensorstore::CopyProgress::AbslStringify(Sink& sink,
                                         
const CopyProgress& a);

Prints a debugging string representation to an std::ostream.