Format Code Repeat Counts?

[jschwab]

Are repeat counts supported Python's str.format() in some fashion?

In Fortran my format strings can have repeat counts.

<pseudocode>
write(*, fmt="3F8.3") [1, 2, 3]
   1.000  2.000   3.000
</pseudocode>

I don't think printf-style format codes, which is what'd I'd
previously used in Python, allow for repeat counts.

As a more concrete example, say I have several sets of letters in a
list of strings
     letters = ["aeiou", "hnopty", "egs", "amsp"]
and I wanted to build a regular expression string out of them like
     re_str <==> "[aeiou][hnopty][egs][amsp]"
Right now, the best I've got that doesn't require an explicit string
like "[{1}][{2}][{3}][{4}]" is
     re_str = "".join(map(lambda x: "[{0}]".format(x), letters))

Is there a better way?

Thanks,
Josiah