This function returns a neighborhood that can be used to “flip” variables in a local search problem involving binary variables (those with a value of 0 or 1).

The function defines a neighborhood that flips the value of a single variable in vars. Specifically, for each variable in vars, there is a neighbor in the neighborhood that flips its value (a change from 0 to 1, or from 1 to 0). The optional argument name, if supplied, becomes the name of the returned neighborhood.