def FindFileContainingSymbol(self, symbol):
    """Finds the file descriptor proto containing the specified symbol.

    The symbol should be a fully qualified name including the file descriptor's
    package and any containing messages. Some examples:

    'some.package.name.Message'
    'some.package.name.Message.NestedEnum'
    'some.package.name.Message.some_field'

    The file descriptor proto containing the specified symbol must be added to
    this database using the Add method or else an error will be raised.

    Args:
      symbol: The fully qualified symbol name.

    Returns:
      The file descriptor proto containing the symbol.

    Raises:
      KeyError if no file contains the specified symbol.
    """
    try:
      return self._file_desc_protos_by_symbol[symbol]
    except KeyError:
      # Fields, enum values, and nested extensions are not in
      # _file_desc_protos_by_symbol. Try to find the top level
      # descriptor. Non-existent nested symbol under a valid top level
      # descriptor can also be found. The behavior is the same with
      # protobuf C++.
      top_level, _, _ = symbol.rpartition('.')
      try:
        return self._file_desc_protos_by_symbol[top_level]
      except KeyError:
        # Raise the original symbol as a KeyError for better diagnostics.
        raise KeyError(symbol)
Finds the file descriptor proto containing the specified symbol.

    The symbol should be a fully qualified name including the file descriptor's
    package and any containing messages. Some examples:

    'some.package.name.Message'
    'some.package.name.Message.NestedEnum'
    'some.package.name.Message.some_field'

    The file descriptor proto containing the specified symbol must be added to
    this database using the Add method or else an error will be raised.

    Args:
      symbol: The fully qualified symbol name.

    Returns:
      The file descriptor proto containing the symbol.

    Raises:
      KeyError if no file contains the specified symbol.
    
deps/protobuf/python/google/protobuf/descriptor_database.py