code: def get_regression_val(self, data_line):
      data_line = data_line.lstrip()
      ca_end_position = 0
      if data_line.startswith("ca"):
          ca_end_position = 2
      separator_position = data_line.find("|")
      return float(data_line[ca_end_position:separator_position])
  
file_path: vowpal_wabbit/demo/cats/utility/ap_regression_data_join.py
imports: import sys
  import getopt
  import math
label_desc: Use image node_id 3 for calling the PredictDataJoiner_ap obj's underlying member method code with example usage: obj.get_regression_val(data_line) and returns: float