class_docstr: Raised if a file cannot be opened.
class_docstr_tok: ["Raised","if","a","file","can","not","be","opened","."]
code: def format_message(self):
      return "Could not open file {}: {}".format(
          self.ui_filename, self.message
      )
  
imports: from ._compat import filename_to_ui
  from ._compat import get_text_stderr
  from ._compat import PY2
  from .utils import echo
label_desc: Use image node_id 2 for calling the FileError obj's underlying member method code with example usage: obj.format_message() and returns: str