Every method should have documentation above the method definition that fits this basic model...
 
# Render the specified item, with the specified options.
#
# ==== Parameters
# thing<String, Symbol, nil>::
#   The thing to render. This will default to the current action
# opts<Hash>:: An options hash (see below)
#
# ==== Options (opts)
# :format<Symbol>:: A registered mime-type format
# :template<String>::
#   The path to the template relative to the template root
# :status<~to_i>::
#   The status to send to the client. Typically, this would
#   be an integer (200), or a Merb status code (Accepted)
# :layout<~to_s>::
#   A layout to use instead of the default. This should be
#   relative to the layout root. By default, the layout will
#   be either the controller_name or application. If you
#   want to use an alternative content-type than the one
#   that the base template was rendered as, you will need
#   to do :layout => “foo.#{content_type}” (i.e. “foo.json”)
#
# ==== Returns
# String:: The rendered template, including layout, if appropriate.
#
# ==== Raises
# TemplateNotFound::
#   There is no template for the specified location.
#
# ==== Alternatives
# If you pass a Hash as the first parameter, it will be moved to
# opts and “thing” will be the current action
#
#—
# @public
def render(thing = nil, opts = {})
  <snip>
end