class_docstr: A collection of protobufs dynamically constructed by descriptor protos.
class_docstr_tok: ["A","collection","of","protobufs","dynamically","constructed","by","descriptor","protos","."]
docstr: Gets the already built FileDescriptor containing the specified symbol.
  
  Args:
    symbol (str): The name of the symbol to search for.
  
  Returns:
    FileDescriptor: Descriptor for the file that contains the specified
    symbol.
  
  Raises:
    KeyError: if the file cannot be found in the pool.
code: def _InternalFindFileContainingSymbol(self, symbol):
      """Gets the already built FileDescriptor containing the specified symbol.
  
      Args:
        symbol (str): The name of the symbol to search for.
  
      Returns:
        FileDescriptor: Descriptor for the file that contains the specified
        symbol.
  
      Raises:
        KeyError: if the file cannot be found in the pool.
      """
      try:
          return self._descriptors[symbol].file
      except KeyError:
          pass
  
      try:
          return self._enum_descriptors[symbol].file
      except KeyError:
          pass
  
      try:
          return self._service_descriptors[symbol].file
      except KeyError:
          pass
  
      try:
          return self._top_enum_values[symbol].type.file
      except KeyError:
          pass
  
      try:
          return self._file_desc_by_toplevel_extension[symbol]
      except KeyError:
          pass
  
      # Try fields, enum values and nested extensions inside a message.
      top_name, _, sub_name = symbol.rpartition(".")
      try:
          message = self.FindMessageTypeByName(top_name)
          assert (
              sub_name in message.extensions_by_name
              or sub_name in message.fields_by_name
              or sub_name in message.enum_values_by_name
          )
          return message.file
      except (KeyError, AssertionError):
          raise KeyError("Cannot find a file containing %s" % symbol)
  
imports: import collections
  import warnings
  from google.protobuf import descriptor
  from google.protobuf import descriptor_database
  from google.protobuf import text_encoding
label_desc: Use image node_id 18 for calling the DescriptorPool obj's underlying member method code with example usage: obj._InternalFindFileContainingSymbol(symbol) and returns: self, self, self, self, self, message