Use VTK's legacy reader to read a file

def read_legacy(filename):
    """Use VTK's legacy reader to read a file"""
    reader = vtk.vtkDataSetReader()
    reader.SetFileName(filename)
    # Ensure all data is fetched with poorly formated legacy files
    reader.ReadAllScalarsOn()
    reader.ReadAllColorScalarsOn()
    reader.ReadAllNormalsOn()
    reader.ReadAllTCoordsOn()
    reader.ReadAllVectorsOn()
    # Perform the read
    reader.Update()
    output = reader.GetOutputDataObject(0)
    if output is None:
        raise AssertionError('No output when using VTKs legacy reader')
    return vtki.wrap(output)