'This overrides the dict.get method, providing type checking
but otherwise equivalent functionality.'

def get(self, key, default=0.0):

    try:
        (i, j) = key
        assert (isintlike(i) and isintlike(j))
    except (AssertionError, TypeError, ValueError):
        raise IndexError('index    must    be    a    pair    of    integers')
    if ((i < 0) or (i >= self.shape[0]) or (j < 0) or (j >= self.shape[1])):
        raise IndexError('index    out    of    bounds')
    return dict.get(self, key, default)
