class Jekyll::Converters::SmartyPants

For more info on converters see jekyllrb.com/docs/plugins/converters/
SmartyPants converter.

def convert(content)

Returns a String of the converted content.

content - String content of file (without front matter).

Logic to do the content conversion. 
def convert(content)
  document = Kramdown::Document.new(content, @config)
  html_output = document.to_html.chomp
  if @config["show_warnings"]
    document.warnings.each do |warning|
      Jekyll.logger.warn "Kramdown warning:", warning.sub(%r!^Warning:\s+!, "")
    end
  end
  html_output
end

def initialize(config) 

def initialize(config)
  Jekyll::External.require_with_graceful_fail "kramdown" unless defined?(Kramdown)
  @config = config["kramdown"].dup || {}
  @config[:input] = :SmartyPants
end

def matches(_ext)

Returns true if it matches, false otherwise.

ext - The String extension to check.

Takes one argument: the file's extension (including the dot).
Does the given extension match this converter's list of acceptable extensions? 
def matches(_ext)
  false
end

def output_ext(_ext)

Returns The String output file extension.

ext - The String extension or original file.

Public: The extension to be given to the output file (including the dot). 
def output_ext(_ext)
  nil
end