import re
regex = re.compile(r"^((?:.*\n){5})((?:.*\n){5})", flags=re.MULTILINE)
test_str = ("1\n"
"2\n"
"3\n"
"4\n"
"5\n"
"6\n"
"7\n"
"8\n"
"9\n"
"10\n"
"11\n"
"12\n"
"13\n"
"14\n"
"15\n"
"16\n"
"17\n"
"18\n"
"19\n"
"20\n")
subst = "$1"
result = regex.sub(subst, test_str)
if result:
print(result)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Python, please visit: https://docs.python.org/3/library/re.html