def get_draft_or_current_value(field_name, review_request):
    """Returns the draft or current field value from a review request.

    If a draft exists for the supplied review request, return the draft's
    field value for the supplied field name, otherwise return the review
    request's field value for the supplied field name.
    """
    if review_request.draft:
        fields = review_request.draft[0]
    else:
        fields = review_request

    return fields[field_name]