# File lib/tree.rb, line 711
    def siblings(cidr)
        # validate object
        if ( !cidr.kind_of?(NetAddr::CIDR) )
            begin
                cidr = NetAddr::CIDR.create(cidr)
            rescue Exception => error
                raise ArgumentError, "Provided argument raised the following " +
                                     "errors: #{error}"
            end
        end

        list = []
        find_parent(cidr).tag[:Subnets].each do |entry|
            if (!cidr.cmp(entry))
                list.push( NetAddr.cidr_build(entry.version, entry.to_i(:network), entry.to_i(:netmask)) )
            end
        end

        return(list)
    end