if at 'go 1.16' or lower.

The go command will automatically download modules as needed during ordinary
execution. The "go mod download" command is useful mainly for pre-filling
the local cache or to compute the answers for a Go module proxy.

By default, download writes nothing to standard output. It may print progress
messages and errors to standard error.

	// relative position's column information may be bogus (it's
	// typically generated code and we can't say much about the
	// original source at that point but for the file:line info
	// that's provided via a line directive).
	// TODO(gri) This may not be true if we have an inlining base.
	// We may want to differentiate at some point.
	format(w, p.RelFilename(), p.RelLine(), p.RelCol(), showCol)

					// We don't know how long the actual write loop would have taken if
					// the buffer were full, so just guess and double the duration so that
					// the next attempt can make twice as much progress toward filling it.
					d *= 2
				}
			} else if next, ok := nextTimeout(actual); !ok {
				t.Fatalf("Write took %s; expected at most %s", actual, want)
			} else {

  //   by the function itself. We can verify that the linear map given by the
  //   VJP are einsums with the equations "ji->ij" and "i->ii" respectively,
  //   where the latter represents 'un-tracing', or filling the diagonal with
  //   the input axis and non-diagonal entries are zeros.
  //        Furthermore, recall that matrix multiplication, which is
  //   represented by the equation "ab,bc->ac", has its VJPs given by the

	}
	if h.UseLocationHost {
		// exchanging req.Host with the backend location is necessary for backends that act on the HTTP host header (e.g. API gateways),
		// because req.Host has preference over req.URL.Host in filling this header field
		newReq.Host = h.Location.Host
	}

	// create the target location to use for the reverse proxy
	reverseProxyLocation := &url.URL{Scheme: h.Location.Scheme, Host: h.Location.Host}

	waitunlockf          func(*g, unsafe.Pointer) bool
	waitlock             unsafe.Pointer
	waitTraceSkip        int
	waitTraceBlockReason traceBlockReason

	syscalltick uint32
	freelink    *m // on sched.freem
	trace       mTraceState

	// these are here because they are too large to be on the stack
	// of low-level NOSPLIT functions.
	libcall    libcall
	libcallpc  uintptr // for cpu profiler

// IsValid reports whether the position is valid.
func (pos *Position) IsValid() bool { return pos.Line > 0 }

// String returns a string in one of several forms:
//
//	file:line:column    valid position with file name
//	file:line           valid position with file name but no column (column == 0)
//	line:column         valid position without file name
//	line                valid position without file name and no column (column == 0)

	seqlock atomic.Uintptr // seqlock indicating that this M is writing to a trace buffer.
	buf     [2]*traceBuf   // Per-M traceBuf for writing. Indexed by trace.gen%2.
	link    *m             // Snapshot of alllink or freelink.
}

// pTraceState is per-P state for the tracer.
type pTraceState struct {
	traceSchedResourceState

	// mSyscallID is the ID of the M this was bound to before entering a syscall.
	mSyscallID int64

	Prefix bool
}

// Execute reads and executes script, writing the output to log.
//
// Execute stops and returns an error at the first command that does not succeed.
// The returned error's text begins with "file:line: ".
//
// If the script runs to completion or ends by a 'stop' command,
// Execute returns nil.
//
// Execute does not stop background commands started by the script

	} else {
		data, err = lockedfile.Read(gomodActual)
	}
	if err != nil {
		return nil, nil, err
	}

	f, err = modfile.Parse(gomod, data, fix)
	if err != nil {
		// Errors returned by modfile.Parse begin with file:line.
		return nil, nil, fmt.Errorf("errors parsing %s:\n%w", gomod, err)
	}
	if f.Go != nil && gover.Compare(f.Go.Version, gover.Local()) > 0 {
		toolchain := ""
		if f.Toolchain != nil {
			toolchain = f.Toolchain.Name