How to compute unseen bi-grams in a corpus (for Good-Turing Smoothing)

Consider a (somewhat nonsensical) sentence – “I see saw a see saw”

The observed bi-grams would be:
“I see”

“see saw”

“saw a”

and,

“a see”.

My aim is to smoothen out the probability mass of the bi-gram probabilities by using Good-Turing smoothing. For this, I need to find the count of unseen bi-grams, i.e., bi-grams with a frequency count of 0.

How do I do this?

1) Would this be a list of all bi-grams formed by using 2 non-consecutive words? For example, “I saw”, “saw saw”, “a I”, etc.?

2) Would repetitions of the same word be included as bi-grams? Eg. “I I”, “see see”, etc.?