code: def __setitem__(self, key, value):
      data, period = self.make_pattern(value[0], value[1])
      self._data[self._index] = data
      self._atlas[key] = [
          self._index / float(self._data.shape[0]),
          period,
      ]
      self._index += 1
      self._dirty = True
  
file_path: vispy/vispy/visuals/line/dash_atlas.py
imports: from functools import lru_cache
  import numpy
label_desc: Use image node_id 3 for calling the DashAtlas obj's underlying member method code with example usage: obj.__setitem__(key, value) without return types