def node_count(shape):
    """Total number of nodes.

    The total number of nodes in a structured grid with dimensions given
    by the tuple, *shape*. Where *shape* is the number of node rows and
    node columns.

    >>> from landlab.utils.structured_grid import node_count
    >>> node_count((3, 4))
    12
    """
    assert len(shape) == 2
    return shape[0] * shape[1]