}
		}
	}
	if !opts.allowDuplicateUsages {
		seen := make(map[certificates.KeyUsage]bool, len(csr.Spec.Usages))
		for i, usage := range csr.Spec.Usages {
			if seen[usage] {
				allErrs = append(allErrs, field.Duplicate(specPath.Child("usages").Index(i), usage))
			}
			seen[usage] = true
		}
	}

		}

		src, err := os.ReadFile(a.genfile)
		if err != nil {
			log.Fatalf("can't read %s: %v", a.genfile, err)
		}
		seen := make(map[string]bool, len(a.ops))
		for _, m := range rxOp.FindAllSubmatch(src, -1) {
			seen[string(m[1])] = true
		}
		for _, op := range a.ops {
			if !seen[op.name] {
				log.Fatalf("Op%s%s has no code generation in %s", a.name, op.name, a.genfile)
			}
		}
	}
}

			for _, vt := range seen[val] {
				if Identical(v.typ, vt.typ) {
					err := check.newError(DuplicateCase)
					err.addf(&v, "duplicate case %s in expression switch", &v)
					err.addf(atPos(vt.pos), "previous case")
					err.report()
					continue L
				}
			}
			seen[val] = append(seen[val], valueType{v.Pos(), v.typ})
		}
	}
}

			// (quadratic algorithm, but these lists tend to be very short)
			for _, vt := range seen[val] {
				if Identical(v.typ, vt.typ) {
					err := check.newError(DuplicateCase)
					err.addf(&v, "duplicate case %s in expression switch", &v)
					err.addf(vt.pos, "previous case")
					err.report()
					continue L
				}
			}
			seen[val] = append(seen[val], valueType{v.Pos(), v.typ})
		}
	}
}

	}
	return nil
}

type shuffleFlag struct {
	on   bool
	seed *int64
}

func (f *shuffleFlag) String() string {
	if !f.on {
		return "off"
	}
	if f.seed == nil {
		return "on"
	}
	return fmt.Sprintf("%d", *f.seed)
}

func (f *shuffleFlag) Set(value string) error {
	if value == "off" {
		*f = shuffleFlag{on: false}
		return nil

	recent [128][4]uint64

	// complete history for seen
	mu sync.Mutex
	m  map[uint64]bool
}

// seen records that h has now been seen and reports whether it was seen before.
// When seen returns false, the caller is expected to print a report for h.
func (d *dedup) seen(h uint64) bool {
	d.mu.Lock()
	if d.m == nil {
		d.m = make(map[uint64]bool)
	}
	seen := d.m[h]
	d.m[h] = true
	d.mu.Unlock()

And we know that editors can't provide a lot of support (like completion) for `dict`s, because they can't know their keys and value types.

We can do better...

## What makes a dependency

Up to now you have seen dependencies declared as functions.

But that's not the only way to declare dependencies (although it would probably be the more common).

The key factor is that a dependency should be a "callable".

		size, err := content.Seek(0, io.SeekEnd)
		if err != nil {
			return 0, errSeeker
		}
		_, err = content.Seek(0, io.SeekStart)
		if err != nil {
			return 0, errSeeker
		}
		return size, nil
	}
	serveContent(w, req, name, modtime, sizeFunc, content)
}

// errSeeker is returned by ServeContent's sizeFunc when the content
// doesn't seek properly. The underlying Seeker's error text isn't

// If there is no such path, the result is nil.
func findPath(objMap map[Object]*declInfo, from, to Object, seen map[Object]bool) []Object {
	if seen[from] {
		return nil
	}
	seen[from] = true

	for d := range objMap[from].deps {
		if d == to {
			return []Object{d}
		}
		if P := findPath(objMap, d, to, seen); P != nil {
			return append(P, d)
		}
	}

	return nil
}

// If there is no such path, the result is nil.
func findPath(objMap map[Object]*declInfo, from, to Object, seen map[Object]bool) []Object {
	if seen[from] {
		return nil
	}
	seen[from] = true

	for d := range objMap[from].deps {
		if d == to {
			return []Object{d}
		}
		if P := findPath(objMap, d, to, seen); P != nil {
			return append(P, d)
		}
	}

	return nil
}