def interpolate(item = self, parent = nil)
      item = render item, parent
      item.is_a?(Hash) ? ::Mash.new(item) : item
    end
def interpolate(item = self, parent = nil)
      item = render item, parent
      item.is_a?(Hash) ? ::Mash.new(item) : item
    end
Interpolate provides a means of externally using Ruby string
 interpolation mechinism.

 @example
   node[:ldap][:basedir] = '/opt'
   node[:ldap][:homedir] = '%{basedir}/openldap/slap/happy'

   interpolate(node[:ldap])[:homedir]  # => "/opt/openldap/slap/happy"

 @param [String] item
   The string to interpolate.

 @param [String, Hash] parent
   The string used for substitution.

 @return [String]
   The interpolated string.

 @api public