def __init__(self, groups=None):
        super(GroupedRequirements, self).__init__(NamedRequirements)
        self.groups = groups or self.default_groups
        self.filename = None
        self.create_default_groups()
def find_files(pattern, root):
  """Return all the files matching pattern below root dir."""
  for path, _, files in os.walk(root):
    for filename in fnmatch.filter(files, pattern):
      yield os.path.join(path, filename)