append string python

var1 = "foo"
var2 = "bar"
var3 = f"{var1}{var2}"
print(var3)                       # prints foobar

# Concatenation
string1 = "str"
string2 = "ing"
string3 = string1 + string2
# string3 is str + ing which is 'string'
# OR
print(string1 + string2)            # prints 'string' 

# Format
string3 = f"{string1}{string2}"     # prints 'string'

var1 = "foo"
var2 = "bar"
var3 = var1 + var2

def add_Is(op):
  if len(op) >= 2 and op[:2] == 'Is':
    return op
  return 'Is' + op
print(add_Is('Ho'))

'Hello '+'World'