python接受命令选项-h

python在用命令行的时候能够接受很多参数，到底是如何接受那些参数和选项呢？

import sys, getopt

opts, args = getopt.getopt(sys.argv[1:], "hi:o:")
input_file=""
output_file=""
 
for op, value in opts:
    if op == "-i":
        input_file = value
    elif op == "-o":
        output_file = value
    elif op == "-h":
        usage()
        sys.exit()