[python] join 함수

# '구분자'.join()

print('_'.join(['a', 'b', 'c']))   #a_b_c
print('_'.join(('a', 'b')))     #a_b
print('_'.join('abcd'))         #a_b_c_d

#print('_'.join([1,2,3]))  #TypeError: sequence item 0: expected str instance, int found
print('_'.join(map(str, [1,2,3])))  #1_2_3
print('_'.join(['1','2','3']))    #1_2_3