```ruby
require 'prawn'

module Mortalical
  module Calendar
    def self.generate
      Prawn::Document.generate("hello.pdf") do |pdf|
        pdf.font_families.update("LeagueGothic" => {
          normal: "./LeagueGothic-Regular.ttf"
        })
        pdf.font "LeagueGothic"
        pdf.text "Hello World!"
      end
    end
  end
end```

Add date and time calculating functions
user
```ruby
require 'prawn'
require 'date'

module Mortalical
  module Calendar
    def self.generate
      Prawn::Document.generate("hello.pdf") do |pdf|
        pdf.font_families.update("LeagueGothic" => {
          normal: "./LeagueGothic-Regular.ttf"
        })
        pdf.font "LeagueGothic"
        pdf.text year_data(2015).inspect
      end
    end

    private
    def self.year_data(year)
      months = (1..12).map do |month|
        days_in_month(year, month)
      end

      {
        year: year,
        months: months,
        first_day: first_day_of_year(year)
      }
    end

    def self.days_in_month(year, month)
      (Date.new(year, 12, 31) << (12-month)).day
    end

    # 0=sunday, 1=monday...6=saturday
    def self.first_day_of_year(year)
      Date.new(year, 1, 1).cwday % 7
    end
  end
end```
assistant