code: def _convert_href_samples(samples_df):
      """Convert HREF eyegaze samples to radians."""
      # grab the xpos and ypos channel names
      pos_names = (
          EYELINK_COLS["pos"]["left"][:-1]
          + EYELINK_COLS["pos"]["right"][:-1]
      )
      for col in samples_df.columns:
          if col not in pos_names:  # 'xpos_left' ... 'ypos_right'
              continue
          series = _href_to_radian(samples_df[col])
          samples_df[col] = series
      return samples_df
  
imports: import re
  from datetime import datetime, timedelta, timezone
  import numpy
  from ..._fiff.constants import FIFF
  from ..._fiff.meas_info import create_info
  from ...annotations import Annotations
  from ...utils import _check_pandas_installed, logger, warn
label_desc: Use image node_id 18 for calling a global function with example usage: _convert_href_samples(samples_df) and returns: samples_df