i have this code:

Import packages

import requests
import pandas as pd
import matplotlib.pyplot as plt
from datetime import datetime

Set the start and end date

start_date = '2023-01-01'
end_date = datetime.now().strftime("%Y-%m-%d")

Define the ticker list

tickers_input = input("Enter a list of tickers separated by commas: ")
tickers_list = tickers_input.split(",")
tickers_list = [ticker.strip() for ticker in tickers_list]

Create placeholder for data

data = pd.DataFrame()

Fetch the data

for ticker in tickers_list:
url = f"https://www.alphavantage.co/query?function=TIME_SERIES_DAILY_ADJUSTED&symbol={ticker}&apikey=YVPP8PYIMZMED6ZJ"
response = requests.get(url)
data_json = response.json()
if 'Error Message' in data_json:
print(f"Failed download: {ticker}")
else:
data[ticker] = pd.DataFrame.from_dict(data_json['Time Series (Daily)']).T['4. close']

Print first 5 rows of the data

print(data.head(5))

Convert data to numerical

data = data.apply(pd.to_numeric)

Plot all the close prices

data.plot(figsize=(80, 20))

Show the legend

plt.legend()

Define the label for the title of the figure

plt.title(ticker, fontsize=16)

Define the labels for x-axis and y-axis

plt.ylabel('Kurs', fontsize=14)
plt.xlabel('Date', fontsize=14)

Plot the grid lines

plt.grid(which="major", color='k', linestyle='-.', linewidth=0.5)
plt.show()

and i get this error:

Enter the start date (YYYY-MM-DD): 2023-01-01
Traceback (most recent call last):
File "/home/schaich/Dokumente/Python/USDCHF.py", line 31, in
rates = exchange_rate(start_date, end_date)
File "/home/schaich/Dokumente/Python/USDCHF.py", line 10, in exchange_rate
rates[date.strftime("%Y-%m-%d")] = cr.get_rate("USD", "CHF", date)
File "/home/schaich/.local/lib/python3.10/site-packages/forex_python/converter.py", line 79, in get_rate
raise RatesNotAvailableError("Currency Rates Source Not Ready")
forex_python.converter.RatesNotAvailableError: Currency Rates Source Not Ready