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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 get_shared_volume_path(container_map, vol, instance=None):
 """ Resolves a volume alias of a container configuration or a tuple of two paths to the host and container paths. :param container_map: Container map. :type container_map: dockermap.map.config.main.ContainerMap :param vol: SharedVolume or HostVolume tuple. :type vol: dockermap.map.input.HostVolume | dockermap.map.input.SharedVolume :param instance: Optional instance name. :type instance: unicode | str :return: Tuple of host path and container bind path. :rtype: tuple[unicode | str] """

    if isinstance(vol, HostVolume):
        c_path = resolve_value(vol.path)
        if is_path(c_path):
            return c_path, get_host_path(container_map.host.root, vol.host_path, instance)
        raise ValueError("Host-container-binding must be described by two paths or one alias name.",
                         vol)
    alias = vol.name
    volume_config = resolve_value(container_map.volumes.get(alias))
    h_path = container_map.host.get_path(alias, instance)
    if volume_config and h_path:
        return volume_config.default_path, h_path
    raise KeyError("No host-volume information found for alias {0}.".format(alias))