code: def get_shared_volume_path(container_map, vol, instance=None):
      
      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))
docs: 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]