from functools import reduce

class string(str):

    def __radd__(self, other):
        other = other or ""
        return reduce(str.__add__,("L" , other , "R+" , "R" , self))

    def __add__(self, other):
        other = other or ""
        return reduce(str.__add__,("L" , self , "+" , "R" , other))

print(sum(map(lambda s:string(s),range(10))))
print(reduce(string.__add__,map(lambda s:string(s),range(10))))