'Look for the bottom-right corner of the cell, making note of all row
boundaries.'

def scan_down(self, top, left, right):

    rowseps = {}
    for i in range((top + 1), (self.bottom + 1)):
        if (self.block[i][right] == '+'):
            rowseps[i] = [right]
            result = self.scan_left(top, left, i, right)
            if result:
                (newrowseps, colseps) = result
                update_dict_of_lists(rowseps, newrowseps)
                return (i, rowseps, colseps)
        elif (self.block[i][right] != '|'):
            return None
    return None
