+print_python::print_python()
+ : print_context(std::cout) {}
+print_python::print_python(std::ostream & os)
+ : print_context(os) {}
+
+print_python_repr::print_python_repr()
+ : print_context(std::cout) {}
+print_python_repr::print_python_repr(std::ostream & os)
+ : print_context(os) {}
+