code: def make_cell_struct_dtype(fields):
      """Makes the dtype of a struct composed of cells
  
      fields - the names of the fields in the struct
      """
      return numpy.dtype([(str(x), "|O4") for x in fields])
  
label_desc: Use image node_id 1 for calling a global function with example usage: make_cell_struct_dtype(fields) and returns: numpy