Write a program that converts upper case to lower case, except at the beginning of a sentence, where it converts lower case to upper case. Sentences begin (1) at the start of input, after any number of spaces and newlines, and (2) following each period, after any number of spaces and newlines. For example, if the user types this Is a test. this is ONLY a test. then your program will print This is a test. This is only a test.