code: def compile(pattern, namespaces=None, flags=0, **kwargs):  # noqa: A001
      
  
      if namespaces is not None:
          namespaces = ct.Namespaces(**namespaces)
  
      custom = kwargs.get('custom')
      if custom is not None:
          custom = ct.CustomSelectors(**custom)
  
      if isinstance(pattern, SoupSieve):
          if flags:
              raise ValueError("Cannot process 'flags' argument on a compiled selector list")
          elif namespaces is not None:
              raise ValueError("Cannot process 'namespaces' argument on a compiled selector list")
          elif custom is not None:
              raise ValueError("Cannot process 'custom' argument on a compiled selector list")
          return pattern
  
      return cp._cached_css_compile(pattern, namespaces, custom, flags)
docs: Compile CSS pattern.