python longest word in string

1def longestword(filename):
2	with open(filename,'r+') as f:
3		words = f.read().split()
4		max_len_word = max(words,key=len)
5		max_len = len(max(words,key=len))		
6		print('maximum lenth word in file :',max_len_word)
7		print('lenth is : ',max_len)
8
9longestword('file1.txt')
10
11or 
12
13def longest_word(filename):
14    with open(filename, 'r') as infile:
15              words = infile.read().split()
16    max_len = len(max(words, key=len))
17    return [word for word in words if len(word) == max_len]
18
19print(longest_word('file1.txt'))
20

1def find_longest_word(word_list):  
2    longest_word =  max(word_list, key=len)
3    return longest_word

1max(a_list, key=len)