Export duration interface from definition file

[bhishp]

I am using this lib but the Duration interface is not currently exported. I parse a duration code in my project within a function and want to describe the return type of that function as Duration but as it is not exported, I do not have access to the type.

e.g.

import { parse, Duration } from 'iso8601-duration';
// ^ Complains, no exported member - Duration

export const emptyDuration: Duration = {};

export const parseDuration = (durationCode?: string): Duration => {
  if (!durationCode) {
    return emptyDuration;
  }
  try {
    return parse(durationCode);
  } catch {
    console.warn('Failed to parse durationCode: ', durationCode);
    return emptyDuration;
  }
};