The use of the metadata request is intended for those who have
    acquired scene IDs from a different source. It will return the
    same metadata that is available via the search request.
    
    :param dataset:
    
    :param node:
    
    :param sceneid:
    
    :param api_key:

def metadata(dataset, node, entityids, api_key=None):
    """
    The use of the metadata request is intended for those who have
    acquired scene IDs from a different source. It will return the
    same metadata that is available via the search request.
    
    :param dataset:
    
    :param node:
    
    :param sceneid:
    
    :param api_key:
    """

    payload = {
        "apiKey": api_key,
        "datasetName": dataset,
        "node": node,
        "entityIds": entityids
    }

    return json.dumps(payload)