if predicate is None:
    predicate = lambda s: not s.isspace()

    prefixed_lines = []
    for line in text.splitlines(True):
        if predicate(line):
            prefixed_lines.append(prefix)
        prefixed_lines.append(line)

prefixed_lines = []

if predicate is None:
    for line in text.splitlines(True):
        if not line.isspace():
            prefixed_lines.append(prefix)
        prefixed_lines.append(line)
else:
    for line in text.splitlines(True):
        if predicate(line):
            prefixed_lines.append(prefix)
        prefixed_lines.append(line)

import timeit
import textwrap

with open("Objects/unicodeobject.c") as f:
    text = f.read()

print(f"indent {len(text.splitlines())} lines.")

it = timeit.Timer(lambda: textwrap.indent(text, ' ' * 4))
result = it.repeat(number=1000)
result.sort()
print(f"{result[0]:.4f}msec")