code: def preprocess_header_attrs(header_attrs, flatten_attrs=False):
      """Prepare file header attributes."""
      if header_attrs is not None:
          if flatten_attrs:
              header_attrs = flatten_dict(header_attrs)
          header_attrs = _encode_nc_attrs(header_attrs)  # OrderedDict
      else:
          header_attrs = {}
      header_attrs = _add_history(header_attrs)
      return header_attrs
  
imports: from __future__ import annotations
  import datetime
  import json
  import logging
  from collections import OrderedDict
  import numpy
  import xarray
  from satpy.writers.utils import flatten_dict
label_desc: Use image node_id 14 for calling a global function with example usage: preprocess_header_attrs(header_attrs, flatten_attrs) and returns: header_attrs