def mac(csp, var, value, assignment, removals):
    "Maintain arc consistency."
    return AC3(csp, [(X, var) for X in csp.neighbors[var]], removals)
def mac(csp, var, value, assignment, removals):
    "Maintain arc consistency."
    return AC3(csp, [(X, var) for X in csp.neighbors[var]], removals)
def mac ( csp , var , value , assignment , removals ) : return AC3 ( csp , [ ( X , var ) for X in csp . neighbors [ var ] ] , removals )
Maintain arc consistency.
Maintain arc consistency .