How to Declare a Variable

a=0
print(a) #print 0

1 2	a=0 print(a) #print 0

Redeclare a Variable

We can re-declare the same variable to sting in python lets do that and check if that works

a=0
print(a) #print 0
a= "xyz"
print(a)

a=0

print(a) #print 0

a= "xyz"

print(a)

Run the file
Output
0
xyz

That means we can redeclare the same variable to any data type in python

print("this is string" + 456)

1	print("this is string" + 456)

Output

TypeError: cannot concatenate ‘str’ and ‘int’ objects

This will give type error. As one is the string and other is number so it can not be combined.
Correct error by

print("this is string " + str(456))

1	print("this is string " + str(456))

f= 0
def anyFunction():
    f="different"
    print(f)

anyFunction()
print(f)

f= 0

def anyFunction():

f="different"

print(f)

anyFunction()

print(f)

Output :

different
0

Inside a function value of f is different.
Inside function variable defined locally.
Variable inside a function and outside a function is considered as two different variables by python interpreter.
If we want to change the global value of variable then we need to explicitly tell the function that variable is global
Add global f and run again.

f= 0
def anyFunction():
    global f
    f="different"  # type: str
    print(f)
    
anyFunction()
print(f)

f= 0

def anyFunction():

global f

f="different" # type: str

print(f)

anyFunction()

print(f)

Output:
different
different