A useful operation is to replace a string of several blanks
by exactly one blank. Note that you can't just write
because the " *" willl match any number of blanks
including zero. Thus it will always match at the beginning
of the line, even if there is no blank there.
which will only substitute for a string
that has at least one blank in it.
Try that command on the line in the file "line".
Then rewrite the file "line" and type "ready".