Deposit Tree API
-----------------

The ``Deposit_Tree`` constructor takes the name of a file that contains
FDIC data. Here are the methods that can be applied to a
``Deposit_Tree``.

.. code:: python

    @properrty
    def children()
    '''
    return a list with the tree's children
    '''

    @property
    def branch()
    '''
    get the branch associated with the tree.
    will be None unless the tree is a leaf
    '''

    @property
    def weight()
    '''
    get the tree's weight
    '''

    def set_weight(w)
    '''
    set the tree's weight
    '''

    def is_branch_node()
    '''
    return true if the tree is a leaf, and false otherwise.
    '''

    def is_leaf_node()
    '''
    return true if the tree is a leaf, and false otherwise.
    '''