code: def read_first_available_value(filename, field_name):
      
      if not os.path.exists(filename):
          return None
      with open(filename, 'rb') as csvfile:
          reader = csv.DictReader(csvfile)
          for row in reader:
              value = row.get(field_name)
              if value:
                  return value
      return None
docs: Reads the first assigned value of the given field in the CSV table.