code: def get_symbol(symbol: str) -> Optional[str]:
      """
      This is a helper function to get a companies full
      name based on the stock symbol.
  
      Examples:
  
          ```python
          import janitor.finance
          janitor.finance.get_symbol("aapl")
          ```
  
      Args:
          symbol: This is our stock symbol that we use
              to query the api for the companies full name.
  
      Returns:
          Company full name
      """
      result = requests.get(
          "http://d.yimg.com/autoc."
          + "finance.yahoo.com/autoc?query={}&region=1&lang=en".format(
              symbol
          )
      ).json()
  
      for x in result["ResultSet"]["Result"]:
          if x["symbol"] == symbol:
              return x["name"]
          else:
              return None
  
file_path: pyjanitor/janitor/finance.py
imports: import json
  from datetime import date
  from functools import lru_cache
  from typing import Optional
  import pandas
  import pandas_flavor
  import requests
  from janitor.errors import JanitorError
  from .utils import check, deprecated_alias, is_connected
label_desc: Use image node_id 8 for calling a global function with example usage: get_symbol(symbol) and returns: x, None