This function is equivalent to a series of if statements checking the
item_type enum value, and calling the more specific session id functions
such as hou.nodeBySessionId(). It allows network items to be treated in a
uniform manner by code that is expected to handle a variety of network item
→ hou.NetworkMovableItem or
See hou.NetworkMovableItem.sessionId() for more information.
Raises hou.NotAvailable if you call it from MPlay.