class DefaultPrinting(object):
    """
    The default implementation of printing for SymPy classes.

    This implements a hack that allows us to print elements of built-in
    Python containers in a readable way. Natively Python uses ``repr()``
    even if ``str()`` was explicitly requested. Mix in this trait into
    a class to get proper default printing.

    """

    # Note, we always use the default ordering (lex) in __str__ and __repr__,
    # regardless of the global setting. See issue 2388.
    def __str__(self):
        from sympy.printing.str import sstr
        return sstr(self, order=None)

    __repr__ = __str__
