def _pv_callbacks(opts, key, callbacks)
        raise ArgumentError, "Callback list must be a hash!" unless callbacks.kind_of?(Hash)
        value = _pv_opts_lookup(opts, key)
        if value != nil
          callbacks.each do |message, zeproc|
            if zeproc.call(value) != true
              raise ValidationFailed, "Option #{key}'s value #{value} #{message}!"
            end
          end
        end
      end
def _pv_callbacks(opts, key, callbacks)
        raise ArgumentError, "Callback list must be a hash!" unless callbacks.kind_of?(Hash)
        value = _pv_opts_lookup(opts, key)
        if value != nil
          callbacks.each do |message, zeproc|
            if zeproc.call(value) != true
              raise ValidationFailed, "Option #{key}'s value #{value} #{message}!"
            end
          end
        end
      end
Check a parameter against a hash of proc's.