class SyntaxTree::Params::KeywordFormatter

as well as an optional default value.
Formats the keyword position of the parameters. This includes the label,

def comments 

def comments
  []
end

def format(q) 

def format(q)
  q.format(name)
  if value
    q.text(" ")
    q.format(value)
  end
end

def initialize(name, value) 

def initialize(name, value)
  @name = name
  @value = value
end