def find_variables(fstruct, fs_class=u'default'):
 if (fs_class == u'default'):
  fs_class = _default_fs_class(fstruct)
 return _variables(fstruct, set(), fs_class, set())

def find_variables ( fstruct , fs_class = u'default' ) : if ( fs_class == u'default' ) : fs_class = _default_fs_class ( fstruct ) return _variables ( fstruct , set ( ) , fs_class , set ( ) )
finds all substitutable variables .