为什么文件只打印了一次?

filename='learning_python.txt'
with open(filename) as file_object:
content=file_object.read()
print(content)
lines=file_object.readlines()
for line in lines:
print(line.strip())
file=''
for line in lines:
file+=line.strip()
print(file)

没有缩进,你的程序整个是错的