def __nonzero__(self):  
return bool(self._module_names)<EOL>
Return :code:`False` if no modules have been traced, :code:`True` otherwise.

For example:

    >>> from __future__ import print_function
    >>> import pexdoc.pcontracts, pexdoc.pinspect, sys
    >>> obj = pexdoc.pinspect.Callables()
    >>> if obj:
    ...     print('Boolean test returned: True')
    ... else:
    ...     print('Boolean test returned: False')
    Boolean test returned: False
    >>> obj.trace([sys.modules['pexdoc.pcontracts'].__file__])
    >>> if obj:
    ...     print('Boolean test returned: True')
    ... else:
    ...     print('Boolean test returned: False')
    Boolean test returned: True