UnboundLocalError: local variable 'data' referenced before assignment in class code example

Example 1: UnboundLocalError: local variable 'r' referenced before assignment

r = 0
list = ['apple','lime','orange']
def list_list(x):
    for i in x:
        r +=1
        print r
list_list(list)

Example 2: UnboundLocalError: local variable 'obj' referenced before assignment

UnboundLocalError: local variable 'obj' referenced before assignment