class_docstr: Fake modifier that raises an exception in __init__.
class_docstr_tok: ["Fake","modifier","that","raises","an","exception","in","__init__","."]
docstr: Raise an exception if we weren't provided any prerequisites.
docstr_tok: ["Raise","an","exception","if","we","were","n't","provided","any","prerequisites","."]
code: def __init__(
      self,
      name,
      prerequisites=None,
      optional_prerequisites=None,
      **kwargs,
  ):
      """Raise an exception if we weren't provided any prerequisites."""
      if not prerequisites or len(prerequisites) != 1:
          raise ValueError("Unexpected number of prereqs")
      super().__init__(
          name, prerequisites, optional_prerequisites, **kwargs
      )
      self.register_data_files(
          {
              "url": kwargs["url"],
              "filename": kwargs["filename"],
              "known_hash": kwargs["known_hash"],
          }
      )
  
imports: from unittest import mock
  import pytest
  import yaml
  from satpy.aux_download import DataDownloadMixin
  from satpy.modifiers import ModifierBase
label_desc: Use image node_id 1 to create a new UnfriendlyModifier object from inherited base classes: ModifierBase, DataDownloadMixin with example: obj = UnfriendlyModifier(name, prerequisites, optional_prerequisites)