def fano(data, units=False):
mu = mean(data, time=True)<EOL>var = variance(data, time=True)<EOL>ff = var / mu<EOL>if units is True:<EOL><INDENT>return np.mean(ff)<EOL><DEDENT>else:<EOL><INDENT>return ff<EOL><DEDENT>
Calculate fano factor (FF) of data. Mean and variance are computed across
time.


Parameters
----------   
data : numpy.ndarray 
    1st axis unit, 2nd axis time.
units : bool
    Average `FF`.


Returns
-------
numpy.ndarray
    If units=False, series of unit FFs.
float
    If units=True, mean FF across units.


Examples
--------
>>> fano(np.array([[1, 2, 3, 4, 5, 6], [11, 2, 3, 3, 4, 5]]))
array([ 0.83333333,  1.9047619 ])

>>> fano(np.array([[1, 2, 3, 4, 5, 6], [11, 2, 3, 3, 4, 5]]), units=True)
1.3690476190476191