Simplify main in package.json
Implement several useful util functions with corresponding tests
Implement tests for whitespace rule
Implement tests for whitespaces rule
Implement tests for hexDigit rule
Implement tests for digit19 rule
Implement tests for digit rule
Implement tests for e rule
Implement tests for digits rule
Implement tests for exponent rule
Implement tests for fraction rule
Implement tests for integer rule
Implement tests for number rule
Implement tests for char rule
Implement tests for chars rule
Implement tests for string rule
Implement tests for literal rule
Implement tests for identifier rule
Implement tests for argument rule
Implement tests for arguments rule