This is the sentence,
So you have come? I have been anxiously waiting for you
So, I have read online that the word "So" can have multiple functions and can be of different part of speech depending upon the context. Could be an adverb, interjection, adjective etc
So, what part "So" is playing in the sentence given above? It is said that "So" can function as an interjection if used to describe a surprise... I think it is playing the role of interjection here but this sentence doesn't look too much like a surprise. Please provide your opinion and tell the function "So" is playing here. Thank you!