class_docstr: A class for handling connections and interactions with the CoinBase API.
  
  Attributes:
      api_key (str): API key
      api_secret (str): API secret
      is_connected (bool): Whether or not the API client is connected to CoinBase.
code: def get_coinbase_candle(
      self, symbol: str, granularity: int
  ) -> pd.DataFrame:
      jdocs = []
      current_time = datetime.datetime.now()
      start_time = current_time - datetime.timedelta(
          seconds=granularity
      )
      start_time_iso = start_time.isoformat().split(".")[0] + "-04:00"
      path = (
          "/products/"
          + symbol
          + "/candles?granularity="
          + str(granularity)
          + "&start="
          + start_time_iso
      )
      headers = self.generate_api_headers("GET", path)
      url = _BASE_COINBASE_US_URL + path
      response = requests.get(url, headers=headers)
      candles = response.json()
      for candle in candles:
          dt = datetime.datetime.fromtimestamp(
              candle[0], None
          ).isoformat()
          low, high, open, close, volume = candle[1:]
          jdoc = {
              "symbol": symbol,
              "low": low,
              "high": high,
              "open": open,
              "close": close,
              "volume": volume,
              "timestamp": candle[0],
              "timestamp_iso": dt,
          }
          jdocs.append(jdoc)
      return pd.DataFrame(jdocs)
  
imports: import pandas
  from typing import Dict
  import datetime
  import hmac
  import hashlib
  import time
  import requests
  from collections import OrderedDict
  import base64
  from mindsdb.integrations.handlers.coinbase_handler.coinbase_tables import CoinBaseAggregatedTradesTable
  from mindsdb.integrations.libs.api_handler import APIHandler
  from mindsdb.integrations.libs.const import HANDLER_CONNECTION_ARG_TYPE
  from mindsdb.integrations.libs.response import HandlerStatusResponse, HandlerResponse
  from mindsdb_sql import parse_sql
label_desc: Use image node_id 4 for calling the CoinBaseHandler obj's underlying member method code with example usage: obj.get_coinbase_candle(symbol, granularity) and returns: pd