'Construct a new frequency distribution.  If ``samples`` is
given, then the frequency distribution will be initialized
with the count of each object in ``samples``; otherwise, it
will be initialized to be empty.
In particular, ``FreqDist()`` returns an empty frequency
distribution; and ``FreqDist(samples)`` first creates an empty
frequency distribution, and then calls ``update`` with the
list ``samples``.
:param samples: The samples to initialize the frequency
distribution with.
:type samples: Sequence'

def __init__(self, samples=None):

    Counter.__init__(self, samples)
    self._N = None
