swift 3 error : Argument labels '(_:)' do not match any available overloads
<p>Just converted a project to Swift 3 and cant figure out the following error.</p>

<pre><code>public func currencyString(_ decimals: Int) -&gt; String {

    let formatter = NumberFormatter()
    formatter.numberStyle = .currency
    formatter.maximumFractionDigits = decimals
    return formatter.string(from: NSNumber(self))!
}
</code></pre>

<p>the return line is showing an error "Argument labels '(_:)' do not match any available overloads"</p>

<p>Any idea what needs to change to resolve this</p>