stripping spaces in front of line

[eight02645999 at yahoo.com]

hi
wish to ask a qns on strip
i wish to strip all spaces in front of a line (in text file)

f = open("textfile","rU")
while (1):
        line = f.readline().strip()
        if line == '':
                break
        print line
f.close()

in "textfile", i added some spaces in and then ran the code, it prints
out the lines without the spaces in front. I double checked "textfile"
and it does contains some lines with spaces in front.
Is it true that "readline().strip()" perform the removing of spaces in
front of a line as well? Is it documented anywhere?
I am using Windows environment. thanks