mutable struct Amrex <: AbstractExtractor 
  app::String
  outputPrefix::String
  degreesOfFreedom
end

function init(extractor::Amrex, outputPrefix::String)
  extractor.app = "Amrex"
  extractor.outputPrefix = outputPrefix
  extractor.degressOfFreedom = [ 
            "max_step", 
            "amr.check_int",
            "amr.plot_int",
            "amr.n_cell",
            "amr.max_level"
        ]
end