'@param valid_packages: defaults to rospack list'

def __init__(self, valid_packages=None, rospack=None):

    if (rospack is None):
        self.rospack = rospkg.RosPack()
    else:
        self.rospack = rospack
    if (valid_packages is None):
        valid_packages = self.rospack.list()
    self.valid_packages = valid_packages
    self.deps_1 = {}
    self.deps = {}
