Use the Flex (a fast lexer generator) to generate a lexer. Flex is the tool for generating lexers. Flex implements the algorithm that convert RE to NFA and NFA to DFA for you. So, you only need to write an input source Flex file (filename.l), where you specify a specification of patterns (called rules) of the lexer using Regular Expressions and C code. You are expected to: 1. Describe the skeleton of an input Flex source file (filename.l) and their functionalities. Three sections in the file: definitions, rules and user routines. % \{ Declaration Section %} Definitions section %% Rules Section %% User routines Section 2. Program and implement Flex. Figure 1. Procedure of Implementation on the Flex Script File (.1) - sample.l is a Flex source file containing the specification (rules) in the form of pairs of regular expressions and C code, for identifying tokens in the input text file. - lex.yy.c defines a scanning routine yylex() that uses the specification to recognize tokens. - Lexical analyzer executable is actually the lexer/scanner program (a.out / .exe)! Sample Input (source code text): while (x>1)y=23.00; Sample Output in the form of table