adding code snippets to Loading Data Files in python article.

loading_titanic4.py

import numpy as np
import pandas as pd

# First let's save the link to the excel file
battle_link = 'https://assets.datacamp.com/production/repositories/487/datasets/5e8897e4624f8577ed0d33aeafbe7bd88bfc424b/battledeath.xlsx'

# Next let's load the file into an io.excel.base file
xls = pd.ExcelFile(battle_link)
# Let's see its type
print(type(xls))
# >> <pandas.io.excel._base.ExcelFile>

# Next, let's print the sheet names 
print(xls.sheet_names)
# >>['2002', '2004']