import requests


def get_seed(pulse_url):
    """
    Given a pulse url does a GET request to the Random UChile API to get the seed given by that pulse.
    :param pulse_url: String representing the URL of the pulse.
    :return: A 512-bit random string that can be used as seed by a pseudo random generator.
    """
    response = requests.get(pulse_url)
    return response.json()['pulse']['outputValue']