def insert (source_str, insert_str, pos): return source_str[:pos]+insert_str+source_str[pos:]
>>> shepherd = "Martha" >>> age = 34 >>> # Note f before first quote of string >>> stuff_in_string = f"Shepherd {shepherd} is {age} years old." >>> print(stuff_in_string) Shepherd Martha is 34 years old.
>>> line = 'Kong Panda' >>> index = line.find('Panda') >>> output_line = line[:index] + 'Fu ' + line[index:] >>> output_line 'Kong Fu Panda'