environment/lib/python2.7/site-packages/IPython/core/builtin_trap.py
def remove_builtin(self, key, orig):
        """Remove an added builtin and re-set the original."""
        if orig is BuiltinUndefined:
            del __builtin__.__dict__[key]
        else:
            __builtin__.__dict__[key] = orig
def remove_builtin(self, key, orig):
        """Remove an added builtin and re-set the original."""
        if orig is BuiltinUndefined:
            del __builtin__.__dict__[key]
        else:
            __builtin__.__dict__[key] = orig
Remove an added builtin and re-set the original.