docs: def enabled_plugins(installed_only=True):
      '''
      .. versionadded:: 0.21
  
      Parameters
      ----------
      installed_only : bool, optional
          Only consider enabled plugins that are installed in the Conda
          environment.
  
      Returns
      -------
      list
          List of properties corresponding to each plugin that is **enabled**.
  
          If :data:`installed_only` is True``, only consider plugins:
  
           1. Present in the ``etc/microdrop/plugins/enabled`` directory as a
              link/junction to a **real** directory (i.e., not a link) in the
              ``share/microdrop/plugins/available`` directory.
           2. Matching the name of a package in the Conda environment.
  
          If :data:`installed_only` is ``False``, consider all plugins present in
          the ``etc/microdrop/plugins/enabled`` directory as either a *real*
          directory or a link/junction.
  
      '''
      enabled_path = MICRODROP_CONDA_PLUGINS.joinpath('enabled')
      if not enabled_path.isdir():
          return []
  
      # Construct list of property dictionaries, one per enabled plugin
      # directory.
      enabled_plugins_ = []
      for plugin_path_i in enabled_path.dirs():
          if not installed_only or _islinklike(plugin_path_i):
              # Enabled plugin path is either **a link to an installed plugin**
              # or call explicitly specifies that plugins that are not installed
              # should still be considered.
  
              # Read plugin package info from `properties.yml` file.
              try:
                  with plugin_path_i.joinpath('properties.yml').open('r') as input_:
                      properties_i = yaml.load(input_.read())
              except:
                  logger.info('[warning] Could not read package info: `%s`',
                              plugin_path_i.joinpath('properties.yml'),
                              exc_info=True)
                  continue
              else:
                  properties_i['path'] = plugin_path_i.realpath()
                  enabled_plugins_.append(properties_i)
  
      if installed_only:
          # Only consider enabled plugins that are installed in the Conda
          # environment.
          try:
              # Attempt to look up installed Conda package info for each enabled
              # plugin.
              package_names = [properties_i['package_name']
                               for properties_i in enabled_plugins_]
              installed_info = ch.package_version(package_names, verbose=False)
          except ch.PackageNotFound, exception:
              # Failed to find a corresponding installed Conda package for at
              # least one enabled plugin.
              logger.warning(str(exception))
              available_names = set([package_i['name']
                                     for package_i in exception.available])
              # Only return list of enabled plugins that have a corresponding
              # Conda package installed.
              return [properties_i for properties_i in enabled_plugins_
                      if properties_i['package_name'] in available_names]
  
      # Return list of all enabled plugins, regardless of whether or not they
      # have corresponding Conda packages installed.
      return enabled_plugins_