Retrieves the main routes of the DTS Collection

        Response format expected :
            {
              "@context": "/dts/api/contexts/EntryPoint.jsonld",
              "@id": "/dts/api/",
              "@type": "EntryPoint",
              "collections": "/dts/api/collections/",
              "documents": "/dts/api/documents/",
              "navigation" : "/dts/api/navigation"
            }

        :returns: Dictionary of main routes with their path
        :rtype: dict

def routes(self):
        """ Retrieves the main routes of the DTS Collection

        Response format expected :
            {
              "@context": "/dts/api/contexts/EntryPoint.jsonld",
              "@id": "/dts/api/",
              "@type": "EntryPoint",
              "collections": "/dts/api/collections/",
              "documents": "/dts/api/documents/",
              "navigation" : "/dts/api/navigation"
            }

        :returns: Dictionary of main routes with their path
        :rtype: dict
        """
        if self._routes:
            return self._routes

        request = requests.get(self.endpoint)
        request.raise_for_status()
        data = request.json()
        self._routes = {
            "collections": parse_uri(data["collections"], self.endpoint),
            "documents": parse_uri(data["documents"], self.endpoint),
            "navigation": parse_uri(data["navigation"], self.endpoint)
        }
        return self._routes