help with yaml.dump

Hi,
I'm using yaml with Python and I need to create a yaml file with
alphabet letters and a corresponding coding.

I'd like to have an output like this:

a: 00000
b: 00001
...

and so on.

I wrote this:

for i in alfabeto:
	yaml.dump({i : gmpy.digits(interi,2).zfill(5)}, stream)

but what I get is:

{a: '10110'}
{b: '10110'}
{c: '10110'}
...

Why does it print the parenthesis { } and apexes ' ' ?

Thanks, bye.
Carlo

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