extract goids

Write a function that takes in a text input $($a char vector$)$ and returns the list of Gene Ontology $($GO$)$ term identifiers contained in that text. Assume that each GO term is listed with the $*$word$*"$GO:$"$ followed by a number. Your function should return the list of GO identifiers as a numerical vector. Your function must return the GO identifiers in the order they appear in the text.