Predicate Make::getAThreewayIntersect
Gets a char that is matched by all the edges s1, s2, and s3.
The result is not complete, and might miss some combination of edges that share some character.
Import path
import codeql.regex.nfa.SuperlinearBackTrackingstring getAThreewayIntersect(InputSymbol s1, InputSymbol s2, InputSymbol s3)