IsTree (SWIG)
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.. function:: IsTree(Graph)
   :noindex:

Determines if *Graph* is a connected tree. The function returns a list of [bool, int], where the bool indicates whether *Graph* is a tree and the int is the node id for the root of the tree.

Parameters:

- *Graph*: directed graph (input) 
    A Snap.py directed graph or a network

Return value: 

- list: [bool, int]
    The list consists of two elements: a bool that indicates whether *Graph* is a tree, and an int giving the node id for the root of the tree.


The following example shows how to detect trees in 
:class:`TNGraph` and :class:`TNEANet`::

    import snap

    Graph = snap.GenTree(snap.PNGraph, 3, 3)
    [is_tree, root_id] = snap.IsTree(Graph)
    print("The graph is a tree: %s " % is_tree)
    print("The graph has a root id: %d" % root_id)

    Network = snap.GenTree(snap.PNEANet, 3, 3)
    [is_tree, root_id] = snap.IsTree(Network)
    print("The graph is a tree: %s " % is_tree)
    print("The graph has a root id: %d" % root_id)