question: Was M7 employed by a company acquired by M1 , M2 , and M3 and acquired by M4 , M5 , and M6
query: SELECT count(*) WHERE {
  ?x0 a ns:business.employer .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M1 .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M2 .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M3 .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M4 .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M5 .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M6 .
  M7 ns:people.person.employment_history/ns:business.employment_tenure.company ?x0
  }