code: def save_vtk_streamlines(
      streamlines, filename, to_lps=True, binary=False
  ):
      """Save streamlines as vtk polydata to a supported format file.
  
      File formats can be OBJ, VTK, VTP, FIB, PLY, STL and XML
  
      Parameters
      ----------
      streamlines : list
          list of 2D arrays or ArraySequence
      filename : string
          output filename (.obj, .vtk, .fib, .ply, .stl and .xml)
      to_lps : bool
          Default to True, will follow the vtk file convention for streamlines
          Will be supported by MITKDiffusion and MI-Brain
      binary : bool
          save the file as binary
  
      """
      if to_lps:
          # ras (mm) to lps (mm)
          to_lps = np.eye(4)
          to_lps[0, 0] = -1
          to_lps[1, 1] = -1
          streamlines = transform_streamlines(streamlines, to_lps)
  
      polydata, _ = fury.utils.lines_to_vtk_polydata(streamlines)
      save_polydata(polydata, file_name=filename, binary=binary)
  
imports: import numpy
  from dipy.tracking.streamline import transform_streamlines
  from dipy.utils.optpkg import optional_package
label_desc: Use image node_id 3 for calling a global function with example usage: save_vtk_streamlines(streamlines, filename, to_lps, binary) without return types