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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 flatten(weights, start=0, stop=2):
 """This methods reshapes all values in a dictionary. The indices from start to stop will be flattened into a single index. Args: weights: A dictionary mapping keys to numpy arrays. start: The starting index. stop: The ending index. """

    for key, val in weights.items():
        new_shape = val.shape[0:start] + (-1, ) + val.shape[stop:]
        weights[key] = val.reshape(new_shape)
    return weights