code: def get_formatter(name):
      
      if name in ('self', 'instance', 'this'):
          return af_self
      elif name == 'class':
          return af_class
      elif name in ('named', 'param', 'parameter'):
          return af_named
      elif name in ('default', 'optional'):
          return af_default
  #    elif name in ('anonymous', 'arbitrary', 'unnamed'):
  #        return af_anonymous
      elif name in ('keyword', 'pair', 'pairs'):
          return af_keyword
      else:
          raise ValueError('unknown trace formatter %r' % name)
docs: Return the named formatter function.  See the function
      "set_formatter" for details.