question: Was M2 a person whose country of nationality employed M0 and M1
query: SELECT count(*) WHERE {
  ?x0 ns:business.employer.employees/ns:business.employment_tenure.person M0 .
  ?x0 ns:business.employer.employees/ns:business.employment_tenure.person M1 .
  M2 a ns:people.person .
  M2 ns:people.person.nationality ?x0
  }