code: def get_fn(name):
      
      fn = resource_filename('mbuild', os.path.join('utils', 'reference', name))
      if not os.path.exists(fn):
          raise IOError('Sorry! {} does not exists.'.format(fn))
      return fn
docs: Get the full path to one of the reference files shipped for utils.
  
      In the source distribution, these files are in ``mbuild/utils/reference``,
      but on installation, they're moved to somewhere in the user's python
      site-packages directory.
  
      Parameters
      ----------
      name : str
          Name of the file to load (with respect to the reference/ folder).