====== Accessing Events in a Tree ======

To access the events in a tree no variables need to be assigned to the different branches. 
Instead the leaves are available as properties of the tree, returning the values of the present event.
<code python>
tree.GetEvent(0)
print tree.Z0_MM  # 18558.9
tree.GetEvent(1)
print tree.Z0_MM  # 2896.5
</code>

To iterate over all events, a ''for'' loop can be used directly on the tree object
<code python>
for event in tree:
    print event.Z0_MM
</code>