def save(content, properties = nil)
      content.each do |key, value|
        save_content(key, value)
      end

      update_properties(properties)
      self
    end
def save(content, properties = nil)
      content.each do |key, value|
        save_content(key, value)
      end

      update_properties(properties)
      self
    end
Save one or more files for this resource given by the +content+ hash.
 Metadata properties about the file(s) may be provided in the optional
 +properties+ parameter. The keys in the content hash correspond to the
 file name for this resource, while the values will be the content stored
 for that key.

 Separate calls to save for the same resource will replace existing files,
 and add new ones. Properties on additional calls will be merged with
 existing properties. Nested hashes in properties will also be merged.

 Examples:

   Gemstash::Storage.for("foo").resource("bar").save(baz: "qux")
   Gemstash::Storage.for("foo").resource("bar").save(baz: "one", qux: "two")
   Gemstash::Storage.for("foo").resource("bar").save({ baz: "qux" }, meta: true)

 @param content [Hash{Symbol => String}] files to save, *must not be nil*
 @param properties [Hash, nil] metadata properties related to this resource
 @return [Gemstash::Resource] self for chaining purposes