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let append: ( WebAPI.FetchAPI.headers, ~name: string, ~value: string,) => unit
let delete: (WebAPI.FetchAPI.headers, string) => unit
let get: (WebAPI.FetchAPI.headers, string) => string
let getSetCookie: WebAPI.FetchAPI.headers => array<string>
let has: (WebAPI.FetchAPI.headers, string) => bool
let make: (~init: array<array<string>>=?) => WebAPI.FetchAPI.headers
let make2: (~init: WebAPI.Prelude.any=?) => WebAPI.FetchAPI.headers
let set: ( WebAPI.FetchAPI.headers, ~name: string, ~value: string,) => unit