declare const get: {
  (key: string): (self: Headers) => Option.Option<string>
  (self: Headers, key: string): Option.Option<string>
}

declare const has: { (key: string): (self: Headers) => boolean; (self: Headers, key: string): boolean }

declare const merge: { (headers: Headers): (self: Headers) => Headers; (self: Headers, headers: Headers): Headers }

declare const redact: {
  (key: string | RegExp | ReadonlyArray<string | RegExp>): (self: Headers) => Record<string, string | Redacted.Redacted>
  (self: Headers, key: string | RegExp | ReadonlyArray<string | RegExp>): Record<string, string | Redacted.Redacted>
}

declare const remove: { (key: string): (self: Headers) => Headers; (self: Headers, key: string): Headers }

declare const set: {
  (key: string, value: string): (self: Headers) => Headers
  (self: Headers, key: string, value: string): Headers
}

declare const setAll: { (headers: Input): (self: Headers) => Headers; (self: Headers, headers: Input): Headers }

declare const empty: Headers

declare const fromInput: (input?: Input) => Headers

declare const unsafeFromRecord: (input: Record.ReadonlyRecord<string, string>) => Headers

declare const currentRedactedNames: FiberRef.FiberRef<ReadonlyArray<string | RegExp>>

export interface Headers extends Redactable {
  readonly [HeadersTypeId]: HeadersTypeId
  readonly [key: string]: string
}

type Input =
  | Record.ReadonlyRecord<string, string | ReadonlyArray<string> | undefined>
  | Iterable<readonly [string, string]>

declare const isHeaders: (u: unknown) => u is Headers

declare const schema: Schema.Schema<Headers, Record.ReadonlyRecord<string, string>>

declare const schemaFromSelf: Schema.Schema<Headers>

declare const HeadersTypeId: unique symbol

type HeadersTypeId = typeof HeadersTypeId