reasoning with constraints def any_holds(selfdomainsconstenvother_varsind= )"""returns true if constraint const holds for an assignment that extends env with the variables in other_vars[ind:env is dictionary warningthis has side effects and changes the elements of env ""if ind =len(other_vars)return const holds(envelsevar other_vars[indfor val in domains[var]env dict_union(env,{var:val}no side effectsenv[varval if self any_holds(domainsconstenvother_varsind )return true return false direct implementation of domain splitting the following is direct implementation of domain splitting with arc consistency that uses recursion it finds one solution if one exists or returns false if there are no solutions cspconsistency py -(continued def solve_one(selfdomains=noneto_do=none)"""return solution to the current csp or false if there are no solutions to_do is the list of arcs to check ""new_domains self make_arc_consistent(domainsto_doif any(len(new_domains[var]= for var in new_domains)return false elif all(len(new_domains[var]= for var in new_domains)self display( "solution:"{varselectnew_domains[var]for var in new_domains}return {varselect(new_domains[var]for var in new_domainselsevar self select_var( for in self csp variables if len(new_domains[ ] if vardom dom partition_domain(new_domains[var]self display( splitting"var"into"dom "and"dom new_doms copy_with_assign(new_domainsvardom new_doms copy_with_assign(new_domainsvardom to_do self new_to_do(varnoneself display( adding"to_do if to_do else "nothing""to to_do "return self solve_one(new_doms to_door self solve_one(new_doms to_doversion june