def dispatch(choice):
    if choice == 'a':
        function_a()
    elif choice == 'b':
        function_b()
    elif choice == 'c':
        function_c()
    else:
        print "Invalid choice."

def function_a():
    print "function_a was called."

def function_b():
    print "function_b was called."

def function_c():
    print "function_c was called."

choice=raw_input("Enter a,b or c: ")
dispatch(choice)
