class Sass::Value::ArgumentList

map as well as the positional arguments.
An argument list comes from a rest argument. It’s distinct from a normal {List} in that it may contain a keyword
Sass’s argument list type.

def initialize(contents = [], keywords = {}, separator = ',') 

def initialize(contents = [], keywords = {}, separator = ',')
  super(contents, separator: separator)
  @id = 0
  @keywords_accessed = false
  @keywords = keywords.transform_keys(&:to_s).freeze
end

def keywords 

def keywords
  @keywords_accessed = true
  @keywords
end