environment/lib/python2.7/site-packages/nose/util.py
def ispackage(path):
    """
    Is this path a package directory?

    >>> ispackage('nose')
    True
    >>> ispackage('unit_tests')
    False
    >>> ispackage('nose/plugins')
    True
    >>> ispackage('nose/loader.py')
    False
    """
    if os.path.isdir(path):
        # at least the end of the path must be a legal python identifier
        # and __init__.py[co] must exist
        end = os.path.basename(path)
        if ident_re.match(end):
            for init in ('__init__.py', '__init__.pyc', '__init__.pyo'):
                if os.path.isfile(os.path.join(path, init)):
                    return True
            if sys.platform.startswith('java') and \
                    os.path.isfile(os.path.join(path, '__init__$py.class')):
                return True
    return False
def ispackage(path):
    """
    Is this path a package directory?

    >>> ispackage('nose')
    True
    >>> ispackage('unit_tests')
    False
    >>> ispackage('nose/plugins')
    True
    >>> ispackage('nose/loader.py')
    False
    """
    if os.path.isdir(path):
        # at least the end of the path must be a legal python identifier
        # and __init__.py[co] must exist
        end = os.path.basename(path)
        if ident_re.match(end):
            for init in ('__init__.py', '__init__.pyc', '__init__.pyo'):
                if os.path.isfile(os.path.join(path, init)):
                    return True
            if sys.platform.startswith('java') and \
                    os.path.isfile(os.path.join(path, '__init__$py.class')):
                return True
    return False
Is this path a package directory?

    >>> ispackage('nose')
    True
    >>> ispackage('unit_tests')
    False
    >>> ispackage('nose/plugins')
    True
    >>> ispackage('nose/loader.py')
    False