In this programming assignment, you will be building a lexical analyzer for small programming language and a program to test it. This assignment will be followed by two other assignments to build a parser and interpreter to the same language. You will write a lexical analyzer function, called getNextToken, and a driver program for testing it. The getNextToken function must have the following signature: Lexltem getNextToken (istream& in, int& linenumber); The first argument to getNextToken is a reference to an istream object that the function should read from. The second argument to getNextToken is a reference to an integer that contains the current line number. getNextToken should update this integer every time it reads a newline from the input stream. getNextToken returns a Lexltem object. A Lexltem is a class that contains a token, a string for the lexeme, and the line number as data members. A header file, lex.h, is provided for you. It contains a definition of the Lexitem class, and a definition of an enumerated type of token symbols, called Token. You MUST use the header file that is provided. You may NOT change it. It is recommended to implement the lexical analyzer in one source file, and the main test program in another source file. The testing program is a main() function that takes several command line flags