code: def find(self, package, **kwargs):
          
          if not exists(package):
              return None
          name, path = None, None
          enforce_init = kwargs.pop('enforce_init', True)
          if isdir(package):
              if isfile(join(package, '__init__.py')) or not enforce_init:
                  name, path = basename(package), package
          elif isfile(package) and package.endswith('.py'):
              name, path = splitext(basename(package))[0], package
          if name and path:
              return PackageSpec(name, path)
          return None
docs: Find method.
  
          Args:
              package (str): package to find.
              **kwargs (): additional keyword arguments.
  
          Returns:
              PackageSpec: the PackageSpec corresponding to the package, or None.