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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 extend(dset, array, **attrs):
 """ Extend an extensible dataset with an array of a compatible dtype. :param dset: an h5py dataset :param array: an array of length L :returns: the total length of the dataset (i.e. initial length + L) """

    length = len(dset)
    if len(array) == 0:
        return length
    newlength = length + len(array)
    if array.dtype.name == 'object':  # vlen array
        shape = (newlength,) + preshape(array[0])
    else:
        shape = (newlength,) + array.shape[1:]
    dset.resize(shape)
    dset[length:newlength] = array
    for key, val in attrs.items():
        dset.attrs[key] = val
    return newlength