如何根据某些字符串提取一行和前一行

def extract_lines_with_previous(lines, target_string):
    result = []
    for i in range(1, len(lines)):
        if target_string in lines[i]:
            result.append(lines[i-1] + '\n' + lines[i])
    return result

# 示例用法
text = '''
This is line 1.
This is line 2.
This is line 3.
This is line 4.
This is line 5.
'''

lines = text.split('\n')
target_string = 'line 4'

extracted_lines = extract_lines_with_previous(lines, target_string)
for line in extracted_lines:
    print(line)

This is line 3.
This is line 4.