def maybe_list(l, scalars=(Mapping, string_t)):
 return (l if ((l is None) or is_list(l, scalars)) else [l])

def maybe_list ( l , scalars = ( Mapping , string_t ) ) : return ( l if ( ( l is None ) or is_list ( l , scalars ) ) else [ l ] )
return list of one element if l is a scalar .