code: def _ensure_geometry_column(df):
      """
      Helper function to ensure the geometry column is called 'geometry'.
      If another column with that name exists, it will be dropped.
      """
      if not df._geometry_column_name == "geometry":
          if "geometry" in df.columns:
              df.drop("geometry", axis=1, inplace=True)
          df.rename(
              columns={df._geometry_column_name: "geometry"},
              copy=False,
              inplace=True,
          )
          df.set_geometry("geometry", inplace=True)
  
file_path: geopandas/geopandas/tools/overlay.py
imports: import warnings
  from functools import reduce
  import numpy
  import pandas
  from geopandas import GeoDataFrame, GeoSeries
  from geopandas.array import _check_crs, _crs_mismatch_warn
label_desc: Use image node_id 1 for calling a global function with example usage: _ensure_geometry_column(df) without return types