old_contents: """A module that let you define functions with generator expressions."""
  from expressions import core
  
  
  class Object(core.BaseType):
      """The most generic type."""
      def __setitem__(self, key, value):
          return self._array.__setitem__(key, value)
  
      def __repr__(self):
          return 'Object(%s)' % repr(self._array)
  
new_contents: """A module that let you define functions with generator expressions."""
  from expressions import core
  
  
  class Object(core.BaseType):
      """The most generic type."""
      def __setitem__(self, key, value):
          return self._array.__setitem__(key, value)
  
      def __repr__(self):
          return 'Object(%s)' % repr(self._array)
  
  
  class System(core.BaseType):
      """A class that wrap a generator that have an system of
      equalities."""
      def __setitem__(self, key, value):
          return self._array.__setitem__(key, value)
  
      def __repr__(self):
          return 'System(%s)' % repr(self._array)
subject: add System class for equalities systems