# reqwest.header

## Function

Set a request header or a set of request headers.

## Syntax

```bt
reqwest(url).header(key, value)
reqwest(url).header(headers)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| key | String | No | None | Request header name. |
| value | Any | No | None | Request header value. |
| headers | Object | No | None | Request header mapping object; see below for rules for keys and values. |

## headers object structure

| key | value type | description |
| ------ | ------ | ------ |
| Request header name | Any | Request header value; it will be converted to a string when called. |

## Return value

| Type | Description |
| ------ | ------ |
| Reqwest | Returns the new request builder. |

## Example

```bt
// Set one request header.
request = reqwest('https://example.com').header('Accept', 'text/plain')
result = type(request)

// Output: Reqwest
print result
```

## Notes

- Object or key/value parameters must be passed, otherwise an error will be reported.