code: def write_line(self, lineno, tree=None):
      if tree is None:
          tree = self.tree
      tree.markers.append(lineno)
      tree.write(linemap[lineno] + "\n")
  
file_path: catboost/contrib/tools/cython/Cython/Tests/TestStringIOTree.py
imports: import unittest
  from Cython import StringIOTree
label_desc: Use image node_id 5 for calling the TestStringIOTree obj's underlying member method code with example usage: obj.write_line(lineno, tree) without return types