class_docstr: Provides methods for retrieving data on different cryptocurrencies from
  https://www.cryptodatadownload.com/cdd/.
  
  Attributes
  ----------
  url : str
      The url for collecting data from CryptoDataDownload.
  
  Methods
  -------
  fetch(exchange_name,base_symbol,quote_symbol,timeframe,include_all_volumes=False)
      Fetches data for different exchanges and cryptocurrency pairs.
docstr: Fetches data from the gemini exchange.
  
  Parameters
  ----------
  base_symbol : str
      The base symbol fo the cryptocurrency pair.
  quote_symbol : str
      The quote symbol fo the cryptocurrency pair.
  timeframe : {"d", "h", "m"}
      The timeframe to collect data from.
  
  Returns
  -------
  `pd.DataFrame`
      A open, high, low, close and volume for the specified
      cryptocurrency pair.
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code: def fetch_gemini(
      self, base_symbol: str, quote_symbol: str, timeframe: str
  ) -> pd.DataFrame:
      """
      Fetches data from the gemini exchange.
  
      Parameters
      ----------
      base_symbol : str
          The base symbol fo the cryptocurrency pair.
      quote_symbol : str
          The quote symbol fo the cryptocurrency pair.
      timeframe : {"d", "h", "m"}
          The timeframe to collect data from.
  
      Returns
      -------
      `pd.DataFrame`
          A open, high, low, close and volume for the specified
          cryptocurrency pair.
      """
      if timeframe.endswith("h"):
          timeframe = timeframe[:-1] + "hr"
      filename = "{}_{}{}_{}.csv".format(
          "gemini", quote_symbol, base_symbol, timeframe
      )
      df = pd.read_csv(self.url + filename, skiprows=1)
      df = df[::-1]
      df = df.drop(["Symbol", "Unix Timestamp"], axis=1)
      df.columns = [name.lower() for name in df.columns]
      df = df.set_index("date")
      df = df.reset_index()
      return df
  
imports: import ssl
  import pandas
label_desc: Use image node_id 3 for calling the CryptoDataDownload obj's underlying member method code with example usage: obj.fetch_gemini(base_symbol, quote_symbol, timeframe) and returns: df