old_contents: // @flow
  
  export default function buildFormData(obj: {[key: string]: string}): FormData {
  	let formData = new FormData()
  	for (const key in obj) {
  		if (obj.hasOwnProperty(key)) {
  			formData.append(key, obj[key])
  		}
  	}
  	return formData
  }
  
new_contents: // @flow
  
  export default function buildFormData(obj: {[key: string]: string}): FormData {
  	let formData = new FormData()
  
  	Object.keys(obj).forEach((key: string) => {
  		formData.append(key, obj[key])
  	})
  
  	return formData
  }
  
subject: replace a final hasOwnProperty with Object.keys iteration