"my_value".index() inquiry...

[RodNintendeaux]

So I am learning this .index() thingy and know how to use it for a single character in a string, but I am running into errors trying to attempt to index multiple characters that match. For instance, I am running this code:

# test code (alabaster, can I index all three a's?)
"alabaster".index("a")

It outputs 0, for the first a in the string. But what about 2 and 4? I can run:

my_value = alabaster
my_value[0]
my_value[2]
my_value[4]

...to pull the a's myself, but can I simply call the string of all a's up front?

I have tried all types of coding setups and failed; and searching the web leads me nowhere. Can anyone help me understand this and the limitations (if any) Python has in this scenario?

Synopsis: I am trying to pull all "a" locations for output >>> 0, 2, 4 using .string(). Can I pull all three? Or am I limited to just the first "a" in a string?

Stuck in a loop of my own errors in learning,

-Rod