message: Moving operator << into sparta namespace
  Summary: This allows us using it in the next diff up the stack as part of a product domain.
diff: @@ -233,8 +233,6 @@ class IntervalDomain final : public AbstractDomain<IntervalDomain<Num>> {
  }
  };
  -} // namespace sparta
  -
  template <typename Num>
  inline std::ostream& operator<<(std::ostream& o,
  const sparta::IntervalDomain<Num>& i) {
  @@ -264,3 +262,5 @@ inline std::ostream& operator<<(std::ostream& o,
  return o << "]";
  }
  +
  +} // namespace sparta
  