how to type variable in string in python w3 code example

Example 1: {} string python

txt1 = "My name is {fname}, I'm {age}".format(fname = "John", age = 36)
txt2 = "My name is {0}, I'm {1}".format("John",36)
txt3 = "My name is {}, I'm {}".format("John",36)

#https://www.w3schools.com/python/ref_string_format.asp

Example 2: python string tutorial

print("Hello\nworld") #for a new line "\n"
print("I want to type \"Hello world\" but I can't") #for writing characters used in coding

phrase = "Hello World" #assigning a value
print(phrase) #for printing values

print(phrase.upper()) #for changing the string to upper case. 
# If you change "upper" out with "lower" it will changing the string to lower case.

print(len(phrase)) # printing the length of the string

print(phrase[0]) # giving the first letter of the string
# 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

print(phrase.index("e")) # printing where in the string "e" is
print(phrase.index("llo"))# printing where in the string "llo" is