def unique(iterables):
    """Create an iterable from the iterables that contains each element once.

    :return: an iterable over the iterables. Each element of the result
      appeared only once in the result. They are ordered by the first
      occurrence in the iterables.
    """
    included_elements = set()

    def included(element):
        result = element in included_elements
        included_elements.add(element)
        return result
    return [element for elements in iterables for element in elements
            if not included(element)]
def unique(iterables):
    """Create an iterable from the iterables that contains each element once.

    :return: an iterable over the iterables. Each element of the result
      appeared only once in the result. They are ordered by the first
      occurrence in the iterables.
    """
    included_elements = set()

    def included(element):
        result = element in included_elements
        included_elements.add(element)
        return result
    return [element for elements in iterables for element in elements
            if not included(element)]
def unique ( iterables ) : included_elements = set ( ) def included ( element ) : result = element in included_elements included_elements . add ( element ) return result return [ element for elements in iterables for element in elements if not included ( element ) ]
Create an iterable from the iterables that contains each element once.

    :return: an iterable over the iterables. Each element of the result
      appeared only once in the result. They are ordered by the first
      occurrence in the iterables.
Create an iterable from the iterables that contains each element once .