"Use proper inputs to download stock data"

[Alberto]

Thank you, I changed the problem with potential input values. The thing is that I get "data" - line 41 of only one stock index. However, I need five datasets as the user introduces 5 countries.

Here is the modified code:

import quandl                     #To extract the data from Quandl website
from quandl.errors.quandl_error import NotFoundError #for error handling 
from datetime import date, timedelta                 # to define the date and time, while "timedelta" - for 1 month back
import matplotlib.pyplot as plt      #Plotting library
import pandas as pd                  #Time series working library
from scipy import interpolate        #Scipy library for interpolation 
import numpy as np
from scipy.optimize import leastsq

def MainFormula():
    exchange1, exchange2, exchange3, exchange4, exchange5  = [None]*5    
    while exchange1 is None or exchange2  is None or exchange3  is None or  exchange4  is None or exchange5  is None:
        exchange1, exchange2, exchange3, exchange4, exchange5 = input('Please, enter 5 countries for obtaining corresponding stock indices (with a comma in between): ').split(',')
        try:
            exchange1 = str(exchange1)  #ensure that entered exchage is string type
            exchange2 = str(exchange2)  #ensure that entered exchage is string type
            exchange3 = str(exchange3)  #ensure that entered exchage is string type
            exchange4 = str(exchange4)  #ensure that entered exchage is string type
            exchange5 = str(exchange5)  #ensure that entered exchage is string type
            if exchange1.lower() or exchange2.lower() or exchange3.lower() or exchange4.lower() or exchange5.lower() is "france":
                ticker = "CHRIS/LIFFE_FCE1"
            elif exchange1.lower() or exchange2.lower() or exchange3.lower() or exchange4.lower() or exchange5.lower() is "usa":
                ticker = "MULTPL/SP500_REAL_PRICE_MONTH"
            elif exchange1.lower() or exchange2.lower() or exchange3.lower() or exchange4.lower() or exchange5.lower() is "germany":
                ticker = "CHRIS/EUREX_FDAX1"
            elif exchange1.lower() or exchange2.lower() or exchange3.lower() or exchange4.lower() or exchange5.lower() is "hong_kong":
                ticker = "CHRIS/HKEX_HSI1"    
            elif exchange1.lower() or exchange2.lower() or exchange3.lower() or exchange4.lower() or exchange5.lower() is "india":
                ticker = "NSE/CNX_NIFTY"      
            elif exchange1.lower() or exchange2.lower() or exchange3.lower() or exchange4.lower() or exchange5.lower() is "japan":
                ticker = "NIKKEI/ALL_STOCK"     
            elif exchange1.lower() or exchange2.lower() or exchange3.lower() or exchange4.lower() or exchange5.lower() is "england":
                ticker = "CHRIS/LIFFE_Z1"                 
            elif exchange1.lower() or exchange2.lower() or exchange3.lower() or exchange4.lower() or exchange5.lower() is "china":
                ticker = "WFE/INDEXES_SHANGHAISESSECOMPOSITEINDEX"                    
            date_time = date.today() #define today's date
            ten_years = date_time - timedelta(days=365*10) # define the date one month ago
            end = date_time.strftime("%Y/%m/%d") #make sure that date is in Y-m-d format
            start = ten_years.strftime("%Y/%m/%d") #make sure that date is in Y-m-d format
            global data   #definre dataframe as global
            data = quandl.get(ticker, start_date=start, end_date=end)             
        except (SyntaxError, NotFoundError):
            " "
            print('Incorrect arguments. Please, try another country.')
            ticker = None               
    return "Here are the results"
program = MainFormula()               
print(program)