how can i not output InformationKey when i output my data to vtu with vtkUnstructuredGrid

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I output my data to .vtu with vtkXMLUnstructuredGridWriter.
However, the vtu file always has “InformationKey”. I don’t want to output this information.

the vtu file shown as:

<?xml version="1.0"?>
<VTKFile type="UnstructuredGrid" version="0.1" byte_order="LittleEndian" header_type="UInt32" compressor="vtkZLibDataCompressor">
  <UnstructuredGrid>
    <Piece NumberOfPoints="6" NumberOfCells="0">
      <PointData>
        <DataArray type="Int32" Name="pressure" format="ascii" RangeMin="0" RangeMax="5">
          0 1 2 3 4 5
        </DataArray>
      </PointData>
      <CellData>
      </CellData>
      <Points>
        <DataArray type="Float32" Name="Points" NumberOfComponents="3" format="ascii" RangeMin="0" RangeMax="1.1661903912355949">
          0 0 0 1 0 0
          0 1 0 0 0 1
          1 0 0.4000000059604645 0 1 0.6000000238418579
          <InformationKey name="L2_NORM_RANGE" location="vtkDataArray" length="2">
            <Value index="0">
              0
            </Value>
            <Value index="1">
              1.1661903912
            </Value>
          </InformationKey>
        </DataArray>
      </Points>
      <Cells>
        <DataArray type="Int64" Name="connectivity" format="ascii" RangeMin="1e+299" RangeMax="-1e+299">
        </DataArray>
        <DataArray type="Int64" Name="offsets" format="ascii" RangeMin="1e+299" RangeMax="-1e+299">
        </DataArray>
        <DataArray type="UInt8" Name="types" format="ascii" RangeMin="1e+299" RangeMax="-1e+299">
        </DataArray>
      </Cells>
    </Piece>
  </UnstructuredGrid>
</VTKFile>

from vtkmodules.vtkIOXML import vtkXMLDataSetWriter
from vtkmodules.vtkCommonCore import vtkPoints
import vtkmodules
from vtkmodules.vtkCommonCore import *
from vtkmodules.util import numpy_support
import numpy

if __name__ == '__main__':
    position = vtkPoints()
    position.SetDataType(VTK_FLOAT)
    position.InsertNextPoint(0, 0, 0)
    position.InsertNextPoint(1, 0, 0)
    position.InsertNextPoint(0, 1, 0)
    position.InsertNextPoint(0, 0, 1)
    position.InsertNextPoint(1, 0, .4)
    position.InsertNextPoint(0, 1, .6)

    grid = vtkmodules.vtkCommonDataModel.vtkUnstructuredGrid()
    grid.SetPoints(position)
    data = numpy.arange(0, 6, 1)
    data = numpy_support.numpy_to_vtk(data)
    data.SetName("pressure")
    grid.GetPointData().AddArray(data)

    writer = vtkmodules.vtkIOXML.vtkXMLUnstructuredGridWriter()
    #writer.SetDataModeToAppended()
    writer.SetDataMode(writer.Ascii)
    writer.SetFileName('a.vtu')
    writer.SetInputData(grid)
    writer.Write()