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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def dot(a, b):
 """Dot product of two TT-matrices or two TT-vectors"""

    if hasattr(a, '__dot__'):
        return a.__dot__(b)
    if a is None:
        return b
    else:
        raise ValueError(
            'Dot is waiting for two TT-vectors or two TT-    matrices')