code: def get_rml(self, rml_name, rtn_format="filepath"):
          
  
          try:
              rml_path = self.rml_maps[rml_name]
          except KeyError:
              if rml_name in self.rml_maps.values() or os.path.exists(rml_name):
                  rml_path = rml_name
              else:
                  raise LookupError("rml_name '%s' is not registered" % rml_name)
          if rtn_format == "data":
              with open(rml_path, "rb") as fo:
                  return fo.read()
          return rml_path
docs: returns the rml mapping filepath
  
          rml_name(str): Name of the rml mapping to retrieve
          rtn_format: ['filepath', 'data']