code: def file_tracer(self, filename):
      filename = canonical_filename(os.path.abspath(filename))
      _, ext = os.path.splitext(filename)
      if ext in CYTHON_EXTENSIONS:
          return CythonFileTracer(filename)
      return None
  
imports: import os
  from coverage.plugin import CoveragePlugin, FileTracer, FileReporter
  from coverage.files import canonical_filename
label_desc: Use image node_id 2 for calling the CythonCoveragePlugin obj's underlying member method code with example usage: obj.file_tracer(filename) and returns: None, CythonFileTracer