# File lib/puppet/parser/ast/minus.rb, line 14
14:         def evaluate(scope)
15:             val = @value.safeevaluate(scope)
16:             val = Puppet::Parser::Scope.number?(val)
17:             if val == nil
18:                 raise ArgumentError, "minus operand %s is not a number" % val
19:             end
20:             return -val
21:         end