Update: Sorry, I addressed the wrong point. I thought I read "fat arrow". But my note on not needing the quotes still holds.

The fat arrow is the same as comma. It has the side effect of letting you not quote the left side. So

'level' , '1','id' , 4
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should be exactly the same as

'level' , '1','id' , 4
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as the hash constructor syntax (putting stuff between braces) just wants a list with an even number of elements, taken as alternating keys and values. That's why it works for parameter lists too.

You could actually write

level => '1', id => 4
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and be even less noisy.

—John