// ./prop-types/Iterable.js

import createPropType from 'create-prop-types';
import { Iterable } from 'immutable';

const IterablePropType = createPropType({
  predicate: propValue => Iterable.isIterable(propValue)
});

export default IterablePropType;

import Iterable from './prop-types/Iterable';

export default class MyComponent extends React.Component {
  static propTypes = {
    propA: Iterable,
    propB: Iterable.isRequired
  }
}

import createPropType from 'create-prop-types';

const CustomPropType = createPropType({
  predicate: propValue => (propValue !== 'foo')
});

export default CustomPropType;

import createPropType from 'create-prop-types';

const CustomPropType = createPropType({
  predicate: propValue => ...,
  warnings: {
    missing: (propName, propValue, componentName) => {
      return `Required prop "${propName}" is missing in "${componentName}" component.`;
    }
  }
});

export default CustomPropType;