add in docs that cooccurrence.data.frame in a group by fashion which does not take into account a sequence
does not return self-occurrences and as there is no order (bag of terms) in the output term1 is always smaller than term2, need to formulate this more concisely
while cooccurrence.character goes left to right, maybe need an option right to left also
Note in Biterm Topic Modelling (https://github.com/bnosac/BTM) cooccurrences occur in window which is a bit different
add in docs that cooccurrence.data.frame in a group by fashion which does not take into account a sequence does not return self-occurrences and as there is no order (bag of terms) in the output term1 is always smaller than term2, need to formulate this more concisely while cooccurrence.character goes left to right, maybe need an option right to left also Note in Biterm Topic Modelling (https://github.com/bnosac/BTM) cooccurrences occur in window which is a bit different