2. String

#!/user/bin/env python
# -*- coding:utf-8 -*-
"""
string (scene):
    section : [start:end[:step]]
        containing "start" and does not contain "end"
        string = "1234567"
            1   2   3   4   5   6   7
            0   1   2   3   4   5   6
            -7  -6  -5  -4  -3  -2  -1
            string[:]           result : 1234567
            string[1:4]         result : 234
            string[-6:-3]       result : 234
            string[1:-3]        result : 234
            string[-6:4]        result : 234
            string[::3]         result : 147
            string[::-1]        result : 7654321
            string[-2::-2]      result : 642
            string[-3:-6:-1]    result : 543
            string[4:1:-1]      result : 543
            string[4:-6:-1]     result : 543
            string[-3:1:-1]     result : 543
        string.find() -> int        Return -1 on failure.
        string.index() -> int       Raises ValueError when the substring is not found.
        string.replace(old, new, count) -> string
            count :
                Maximum number of occurrences to replace.
                -1 (the default value) means replace all occurrences.
        string.split([sep], [maxSplit]) ->list
            sep
                The delimiter according which to split the string.
                None (the default value) means split according to any whitespace,
                and discard empty strings from the result.
            maxSplit
                Maximum number of splits to do.
                -1 (the default value) means no limit.
        string.upper()
        string.lower()
        string.title()        words start with upper cased characters and all remaining cased characters have lower case.
        string.capitalize()   make the first character have upper case and the rest lower case.

        string.isupper()
        string.islower()
        string.isalpha()
        string.isdigit()
        string.startswith()
        string.endswith()

        string.center(width, [fillchar])
        string.ljust(width, [fillchar])
        string.rjust(width, [fillchar])

        string.format()
            name = "cxk"
            age = 18
            print("{}, age : {}, you are an idiot".format(name, age))
            print("{0}, age : {1}, you are an idiot".format(name, age))
            print("{}, age : {}, you are an idiot".format(name=name, age=age))

            money = 5.99458
            print("I have {:.2f}¥".formate(money))

        string.strip()
        string.rstrip()
        string.lstrip()

        stirng.join()

    String-Supported operators :
        + * in is == != [] % > <

"""