code: def _proc_empty_strings(col):
      """Replaces empty strings with NaN"""
      s = cudf.Series(col)
      s = s.where(s != "", "NaN")
      return s._column
  
file_path: cudf/python/cudf/cudf/core/tools/numeric.py
imports: import warnings
  import numpy
  import pandas
  import cudf
  from cudf import _lib
  from cudf._lib import strings
  from cudf.api.types import _is_non_decimal_numeric_dtype, is_datetime_dtype, is_string_dtype, is_timedelta_dtype
  from cudf.core.column import as_column
  from cudf.core.dtypes import CategoricalDtype
  from cudf.utils.dtypes import can_convert_to_column
label_desc: Use image node_id 4 for calling a global function with example usage: _proc_empty_strings(col) and returns: s