code: def get(self, twig=None, check_visible=True, check_default=True, **kwargs):
          
          kwargs['check_visible'] = check_visible
          kwargs['check_default'] = check_default
          # print "***", kwargs
          ps = self.filter(twig=twig, **kwargs)
          if not len(ps):
              # TODO: custom exception?
              raise ValueError("0 results found")
          elif len(ps) != 1:
              # TODO: custom exception?
              raise ValueError("{} results found: {}".format(len(ps), ps.twigs))
          else:
              # then only 1 item, so return the parameter
              return ps._params[0]
docs: Get a single parameter from this ParameterSet.  This works exactly the
          same as filter except there must be only a single result, and the Parameter
          itself is returned instead of a ParameterSet.
  
          Also see :meth:`get_parameter` (which is simply an alias of this method)
  
          :parameter str twig: (optional) the search twig - essentially a single
                  string with any delimiter (ie '@') that will be parsed
                  into any of the meta-tags.  Example: instead of
                  b.filter(context='component', component='starA'), you
                  could do b.filter('starA@component').
          :parameter bool check_visible: whether to hide invisible
                  parameters.  These are usually parameters that do not
                  play a role unless the value of another parameter meets
                  some condition.
          :parameter bool check_default: whether to exclude parameters which
                  have a _default tag (these are parameters which solely exist
                  to provide defaults for when new parameters or datasets are
                  added and the parameter needs to be copied appropriately).
                  Defaults to True.
          :parameter **kwargs: meta-tags to search (ie. 'context', 'component',
                  'model', etc).  See :func:`meta` for all possible options.
          :return: the resulting :class:`Parameter`
          :raises ValueError: if either 0 or more than 1 results are found
                  matching the search.