def cert_verify(self, conn, url, verify, cert):
        """Verify a SSL certificate. This method should not be called from user
        code, and is only exposed for use when subclassing the
        :class:`HTTPAdapter <requests.adapters.HTTPAdapter>`.

        :param conn: The urllib3 connection object associated with the cert.
        :param url: The requested URL.
        :param verify: Either a boolean, in which case it controls whether we verify
            the server's TLS certificate, or a string, in which case it must be a path
            to a CA bundle to use
        :param cert: The SSL certificate to verify.
        """
        if url.lower().startswith('https') and verify:

            cert_loc = None

            # Allow self-specified cert location.
            if verify is not True:
                cert_loc = verify

            if not cert_loc:
                cert_loc = extract_zipped_paths(DEFAULT_CA_BUNDLE_PATH)

            if not cert_loc or not os.path.exists(cert_loc):
                raise IOError("Could not find a suitable TLS CA certificate bundle, "
                              "invalid path: {}".format(cert_loc))

            conn.cert_reqs = 'CERT_REQUIRED'

            if not os.path.isdir(cert_loc):
                conn.ca_certs = cert_loc
            else:
                conn.ca_cert_dir = cert_loc
        else:
            conn.cert_reqs = 'CERT_NONE'
            conn.ca_certs = None
            conn.ca_cert_dir = None

        if cert:
            if not isinstance(cert, basestring):
                conn.cert_file = cert[0]
                conn.key_file = cert[1]
            else:
                conn.cert_file = cert
                conn.key_file = None
            if conn.cert_file and not os.path.exists(conn.cert_file):
                raise IOError("Could not find the TLS certificate file, "
                              "invalid path: {}".format(conn.cert_file))
            if conn.key_file and not os.path.exists(conn.key_file):
                raise IOError("Could not find the TLS key file, "
                              "invalid path: {}".format(conn.key_file))
Verify a SSL certificate. This method should not be called from user
        code, and is only exposed for use when subclassing the
        :class:`HTTPAdapter <requests.adapters.HTTPAdapter>`.

        :param conn: The urllib3 connection object associated with the cert.
        :param url: The requested URL.
        :param verify: Either a boolean, in which case it controls whether we verify
            the server's TLS certificate, or a string, in which case it must be a path
            to a CA bundle to use
        :param cert: The SSL certificate to verify.
        
product/gradle-plugin/src/main/python/pip/_vendor/requests/adapters.py