python-当 str 对象属性为“只读”时，这意味着什么？如何修复我的代码？

这是我的代码：

# Get the name of the file and open it
name = input("Enter file:")
handle = open(name)

# Count word frequency 
counts = dict()
for line in handle:
    words = line.split()
    for word in words:
        counts[word] = counts.get(word,0) + 1
        
# Find the most common word
bigcount = None
bigword = None 
for word.count in counts.items():
    if bigcount is None or count > bigcount:
        bigword = word
        bigcount = count
        
# All done
print(bigword, bigcount)

当我调用它并输入消息并按enter键时，会出现AttributeError并说：

 ---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
 in 
     13 bigcount = None
     14 bigword = None
---> 15 for word.count in counts.items():
     16     if bigcount is None or count > bigcount:
     17         bigword = word

AttributeError: 'str' object attribute 'count' is read-only

我应该怎么做才能修复我的代码？什么是“只读”str 对象属性？