I have a TextInput. Instead of showing the actual text entered, when the user enters text I want it to show the password dots / asterisks (`****`) you typically see in apps when typing a password. How can I do this?

```
<TextInput
  style={{ height: 40, borderColor: 'gray', borderWidth: 1 }}
  onChangeText={(text) => this.setState({input: text})}
/>

```