def acroform
      state.store.root.data[:AcroForm] ||= 
        ref!({:DR => acroform_resources, 
              :DA => Prawn::Core::LiteralString.new("/Helv 0 Tf 0 g"),
              :Fields => []})
    end
def acroform
      state.store.root.data[:AcroForm] ||= 
        ref!({:DR => acroform_resources, 
              :DA => Prawn::Core::LiteralString.new("/Helv 0 Tf 0 g"),
              :Fields => []})
    end
The AcroForm dictionary (PDF spec 8.6) for this document. It is
 lazily initialized, so that documents that do not use interactive
 forms do not incur the additional overhead.