code: def _basic_checks(left_df, right_df, how, lsuffix, rsuffix):
      """Checks the validity of join input parameters.
  
      `how` must be one of the valid options.
      `'index_'` concatenated with `lsuffix` or `rsuffix` must not already
      exist as columns in the left or right data frames.
  
      Parameters
      ------------
      left_df : GeoDataFrame
      right_df : GeoData Frame
      how : str, one of 'left', 'right', 'inner'
          join type
      lsuffix : str
          left index suffix
      rsuffix : str
          right index suffix
      """
      if not isinstance(left_df, GeoDataFrame):
          raise ValueError(
              "'left_df' should be GeoDataFrame, got {}".format(
                  type(left_df)
              )
          )
  
      if not isinstance(right_df, GeoDataFrame):
          raise ValueError(
              "'right_df' should be GeoDataFrame, got {}".format(
                  type(right_df)
              )
          )
  
      allowed_hows = ["left", "right", "inner"]
      if how not in allowed_hows:
          raise ValueError(
              '`how` was "{}" but is expected to be in {}'.format(
                  how, allowed_hows
              )
          )
  
      if not _check_crs(left_df, right_df):
          _crs_mismatch_warn(left_df, right_df, stacklevel=4)
  
      index_left = "index_{}".format(lsuffix)
      index_right = "index_{}".format(rsuffix)
  
      # due to GH 352
      if any(left_df.columns.isin([index_left, index_right])) or any(
          right_df.columns.isin([index_left, index_right])
      ):
          raise ValueError(
              "'{0}' and '{1}' cannot be names in the frames being"
              " joined".format(index_left, index_right)
          )
  
file_path: geopandas/geopandas/tools/sjoin.py
imports: from typing import Optional
  import warnings
  import numpy
  import pandas
  from geopandas import GeoDataFrame
  from geopandas.array import _check_crs, _crs_mismatch_warn
label_desc: Use image node_id 2 for calling a global function with example usage: _basic_checks(left_df, right_df, how, lsuffix, rsuffix) without return types