For python variable scopes

For python variable scopes

# Define variable a >>> a = 0 >>> print a0 # define FUNCTION p () >>> def p ():... print a... >>> p () 0 # define the function p2 () >>> def p2 ():... print... a = 3... print a... >>> p2 () # An error occurred while running. external variable a is referenced first and cannot be assigned Traceback (most recent call last): File "<interactive input>", line 1, in <module> File "<interactive input>", line 2, in p2UnboundLocalError: local variable 'A' referenced before assignment # define function p3 () >>> def p3 () :... a = 3 # assign values without referencing... print a... >>> p3 () 3 >>> print a0 # external variable a has not changed