expense or outlay\(s[l:r]\) Indicates that the string subscript is in the\([l,r]\) substrings (closed intervals) consisting of characters within the\(:\) The default value without a preceding number is\(1\), no number after the colon defaults to the length of the string. If the length of the string is equal to the length of the string when\(s=\texttt{abcde}\) when\(s[2:4]=\texttt{bcd}\)，\(s[3:]=\texttt{cde}\)。