'Try to find a C source file for a file path found by the tracer.'

def file_tracer(self, filename):

    if (filename.startswith('<') or filename.startswith('memory:')):
        return None
    c_file = py_file = None
    filename = os.path.abspath(filename)
    if (self._c_files_map and (filename in self._c_files_map)):
        c_file = self._c_files_map[filename][0]
    if (c_file is None):
        (c_file, py_file) = self._find_source_files(filename)
        if (not c_file):
            return None
        self._parse_lines(c_file, filename)
    if (self._file_path_map is None):
        self._file_path_map = {}
    return CythonModuleTracer(filename, py_file, c_file, self._c_files_map, self._file_path_map)
