code: def _set_fid_iid_df(df):
      df["FID_IID"] = (
          df["FID"].astype(str) + "_" + df["IID"].astype(str)
      )
      return (
          df.sort_values(by=["FID", "IID"])
          .drop(columns=["FID", "IID"])
          .set_index(["FID_IID"])
      )
  
file_path: glow/python/glow/gwas/tests/functions.py
imports: import glow.functions
  import numpy
  import pandas
  from pandas.testing import assert_frame_equal
label_desc: Use image node_id 1 for calling a global function with example usage: _set_fid_iid_df(df) and returns: df