execute (DataMapper::Validate::ContextualValidators)

    # File lib/dm-validations/contextual_validators.rb, line 61
          def execute(named_context, target)
            raise(ArgumentError, "validation context #{named_context} doesn't seem to be defined. Known contexts are #{contexts.keys.inspect}") if !named_context || (contexts.length > 0 && !contexts[named_context])
            target.errors.clear!
            result = true
            # note that all? and any? stop iteration on first negative or positive result,
            # so we really have to use each here to make sure all validators are
            # executed
            context(named_context).select { |validator| validator.execute?(target) }.each do |validator|
              result = false unless validator.call(target)
            end

            result
          end