code: def get_lmost_sibling(self):
      if (
          not self._lmost_sibling
          and self.parent
          and self != self.parent.children[0]
      ):
          self._lmost_sibling = self.parent.children[0]
      return self._lmost_sibling
  
file_path: scikit-learn/sklearn/tree/_reingold_tilford.py
imports: import numpy
label_desc: Use image node_id 5 for calling the DrawTree obj's underlying member method code with example usage: obj.get_lmost_sibling() and returns: self