code: def calculate_index(number: str) -> int:
      first_number_as_int = int(number[0])
  
      number_index = Multi_tap.get_index_from_first_digit(
          first_number_as_int
      )
  
      # Add to index the number of the char : "22" -> index += 1
      num_rest_numbers = len(number) - 1
      number_index += num_rest_numbers
  
      return number_index
  
file_path: Ciphey/ciphey/basemods/Decoders/multi_tap.py
imports: from typing import Dict, Optional
  from ciphey.iface import Config, Decoder, ParamSpec, T, U, registry
label_desc: Use image node_id 5 for calling the Multi_tap obj's underlying member method code with example usage: obj.calculate_index(number) and returns: number_index