code: def _resolve(self, path, migration_file):
          
          variables = {}
  
          name = '_'.join(migration_file.split('_')[4:])
          migration_file = os.path.join(path, '%s.py' % migration_file)
  
          with open(migration_file) as fh:
              exec(fh.read(), {}, variables)
  
          klass = variables[inflection.camelize(name)]
  
          instance = klass()
          instance.set_schema_builder(self.get_repository().get_connection().get_schema_builder())
  
          return instance
docs: Resolve a migration instance from a file.
  
          :param migration_file: The migration file
          :type migration_file: str
  
          :rtype: eloquent.migrations.migration.Migration