def load(self, recipe):
        '''load a recipe file into the client, first performing checks, and
           then parsing the file.

           Parameters
           ==========
           recipe: the original recipe file, parsed by the subclass either
               DockerRecipe or SingularityRecipe
 
        '''
        self.recipe = recipe           # the recipe file
        self._run_checks()             # does the recipe file exist?
        self.parse()
load a recipe file into the client, first performing checks, and
           then parsing the file.

           Parameters
           ==========
           recipe: the original recipe file, parsed by the subclass either
               DockerRecipe or SingularityRecipe