In English, there is an implied difference between “the girl downstairs was playing violin” (‘the girl’ implying expected knowledge - “oh, her”) versus “a girl downstairs was playing violin” (‘a girl’ - random, likely unknown).
More broadly “a thing” - one of many, “the thing” - a specific one.
How would that translate to Farsi?
Let’s try not to jinx him, hey? 😅
Also:
…I just wanted a picture…