def calcArea(vertexes):
    """

    :param vertexes:
    :return Float: Area of the polygon, Positive value means clockwise direction, negative counter-clockwise.

    >>> calcArea([Point(0, 0), Point(0, 1), Point(1, 1), Point(1, 0)])
    -1.0

    >>> calcArea([Point(0, 0), Point(1, 0), Point(1, 1), Point(0, 1)])
    1.0
    """
    if not vertexes[0].equals(vertexes[len(vertexes)-1]):
        vertexes.append(vertexes[0])

    prevVertex = None
    sum = 0
    for vertex in vertexes:
        if prevVertex:
            sum += (prevVertex.x*vertex.y-prevVertex.y*vertex.x)
        prevVertex = vertex

    return sum/2