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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _connect(self):
 """ Connect to the EC2 cloud provider. :return: :py:class:`boto.ec2.connection.EC2Connection` :raises: Generic exception on error """

        # check for existing connection
        if self._ec2_connection:
            return self._ec2_connection

        try:
            log.debug("Connecting to EC2 endpoint %s", self._ec2host)

            # connect to webservice
            ec2_connection = boto.ec2.connect_to_region(
                self._region_name,
                aws_access_key_id=self._access_key,
                aws_secret_access_key=self._secret_key,
                is_secure=self._secure,
                host=self._ec2host,
                port=self._ec2port,
                path=self._ec2path,
            )
            # With the loose setting `BOTO_USE_ENDPOINT_HEURISTICS`
            # which is necessary to work around issue #592, Boto will
            # now accept *any* string as an AWS region name;
            # furthermore, it *always* returns a connection object --
            # so the only way to check that we are not going to run
            # into trouble is to check that there *is* a valid host
            # name on the other end of the connection.
            if ec2_connection.host:
                log.debug("EC2 connection has been successful.")
            else:
                raise CloudProviderError(
                    "Cannot establish connection to EC2 region {0}"
                    .format(self._region_name))

            if not self._vpc:
                vpc_connection = None
                self._vpc_id = None
            else:
                vpc_connection, self._vpc_id = self._find_vpc_by_name(self._vpc)

        except Exception as err:
            log.error("Error connecting to EC2: %s", err)
            raise

        self._ec2_connection, self._vpc_connection = (
            ec2_connection, vpc_connection)
        return self._ec2_connection