Substring function library

Hi

How to use substring function in igniiton script modules? Which library to import?

Thanks in advance

Here is an example:str = "This is my string" print str[5:10]which prints “is my”. You can also do this:str = "This is my string" print str[5:]which prints “is my string” and:str = "This is my string" print str[:10]which prints “This is my”.