# записываем строку в начало файла

myf = open('test1.txt', 'r')
memo = myf.read()

ah = open('test1.txt', 'w')
ah.write('New line, text\n\n')
ah.close()

myf_new = open('test1.txt', 'a')
myf_new.write(memo)
myf_new.close()

with open('uu.txt', 'r') as file:
    a=file.readlines()
    a.insert(0, 'New line\n')
with open('uu.txt', 'w') as file:
    file.writelines(a)

with open('uu.txt', 'r+') as f:
	lines = f.readlines()
	f.seek(0)
	f.writelines( ["first line\n"]+lines )

with open('uu.txt', 'r+') as f:
    f.writelines( ["first line\n"]+[f.readlines(),f.seek(0)][0] )

with open('file.txt', 'r+', encoding='utf-8') as fio:
    data = fio.read()
    fio.seek(0)
    fio.write('line\n' + data)