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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 trunk_origin_radii(nrn, neurite_type=NeuriteType.all):
    '''radii of the trunk sections of neurites in a neuron'''
    neurite_filter = is_type(neurite_type)
    return [s.root_node.points[0][COLS.R] for s in nrn.neurites if neurite_filter(s)]