The following tasks should be solved in the order below. Write tests for each step!

• Grade 2: Add a new regular expression to the lexer to describe time values of the form HH:MM, where H and M can be any decimal digits.
• Grade 3: Change the grammar to allow time values to be expressions.
• Grade 4:
  • Add the following keywords: hour, minute and time.
  • Add the hour and minute functions to the grammar of the expressions. For example:
    • hour(12:38)
    • minute(someVariable)
  • Extend the variable declarations to allow time variables:
    • time someVariable;
• Grade 5: Extend the semantic analysis:
  • The parameters of hour and minute must be of type time. The return type of these functions is integer.
  • Assignment to a time variable has to be type correct as well.