code: def write_pp_file(filename,pp_df):
      
      with open(filename,'w') as f:
         f.write(pp_df.to_string(col_space=0,
                                  columns=PP_NAMES,
                                  formatters=PP_FMT,
                                  justify="right",
                                  header=False,
                                  index=False) + '\n')
docs: write a pilot points dataframe to a pilot points file
  
      Parameters
      ----------
      filename : str
          pilot points file to write
      pp_df : pandas.DataFrame
          a dataframe that has columns "x","y","zone", and "value"