code: def _fill_or_assign(df, column, default):
      if column in df.columns:
          df.fillna({column: default}, inplace=True)
      else:
          df[column] = default
  
imports: from collections import defaultdict, namedtuple
  from typing import Iterable
  import warnings
  import numpy
  import pandas
  from ..globalvar import SOURCE, TARGET, WEIGHT, TYPE_ATTR_NAME
  from .element_data import NodeData, EdgeData
  from .indexed_array import IndexedArray
  from .validation import comma_sep, require_dataframe_has_columns
  from .utils import is_real_iterable, zero_sized_array, smart_array_concatenate, smart_array_index
label_desc: Use image node_id 6 for calling a global function with example usage: _fill_or_assign(df, column, default) without return types