how do I type the cb?

type-ex.js

/*
In the scenario below, I have a menu that can be used to render a list
of selectable options that may be of type 'string' or of type 'number'.
It takes a 'onOptionSelect' callback whose arguments can be of either type.

However, some components that render this generic menu may only accept 
string-type selections or may only accept number-type selections. How do I
type onOptionsSelect (or the actual callbacks that get passed in) to account
for this flexibility?
*/

// generic-menu.js

type Props = {
  options: Array<string | number>,
  onOptionSelect: (option: string | number) => void
}

function MyMenu(props: Props) {
  const { onOptionSelect } = this.props

  return (
    <div className="menu">
      <ul>
        {options.map((option, idx) => (
          <li key={idx}>
            <button onClick={onOptionSelect}>{option}</button>
          </li>
        ))}
      </ul>
    </div>
  )
}

// mypage.js

class MyPage extends Component {
  handleSelect = (name: string) => { // this line will have a Flow error since I'm not allowing number types for name arg
    api.post(..., { name })
  }

  render() {
    return (
      <div>
        <h1>My name-picker page</h1>
        <MyMenu 
          options={['tina', 'tammy', 'toby']} 
          onOptionSelect={this.handleSelect} 
        />
      </div>
    )
  }
}