class Pagy::Calendar

def create(unit, vars)

Create a subclass instance by unit name (internal use) 
def create(unit, vars)
  raise InternalError, "unit must be in #{UNITS.inspect}; got #{unit}" unless UNITS.include?(unit)
  name    = unit.to_s
  name[0] = name[0].capitalize
  Object.const_get("Pagy::Calendar::#{name}").new(vars)
end