'Internal method for determining left or right client.
Negative direction is to left'

def horizontal_traversal(self, direction):

    (column, row) = (self.column, self.row)
    column = ((column + direction) % len(self.get_row(row)))
    self.clients.current_index = ((row * self.columns) + column)
    self.group.focus(self.clients.current_client)
